Main article: Speed limit

Speed limits in the United States are set by each state. Speed limits are usually:

• 15-25 mph (25-40 km/h) in a school zone, depending on the state law
• 25–35 mph (40–55 km/h) on residential streets
• 35–45 mph (55–70 km/h) on urban arterial roads
• 50–65 mph (80–105 km/h) on major highways inside cities
• 45–65 mph (70–105 km/h) on rural two-lane roads
• 55–70 mph (90–110 km/h) on rural expressways
• 65–80 mph (105–130 km/h) on rural Interstate highways

The highest limits are usually found in the inland West and the lowest limits are usually found in the Northeast, and some limits fall outside these ranges. For example, some two-lane rural roads in Texas have 75 mph (120 km/h) speed limits, and there are two stretches of Interstate in West Texas with a daytime 80 mph (130 km/h) speed limit for passenger vehicles. In contrast, the highest speed limit on Interstates in Hawaii is 60 mph (95 km/h).

A standard sign indicating a speed limit of 80 miles per hour (mph), a night-time speed limit of 65 mph, and a truck speed limit of 55 mph

Charts

Speed limits

This table contains the usual daytime speed limit, in miles per hour, on typical roads in each category. This is usually, but not always, the statutory speed limit.

Some states have lower truck speed limits applicable to heavy trucks.

State	Freeway (rural)	Freeway (urban)	4 lane (rural)	2 lane (rural)	County (rural)	Residential (urban)	School Zones
Alabama	70	60	65	55	35-45
Alaska	65	65	65	65	50	25	20
Arizona	75	65	65	65	65	25	15
Arkansas	70	65	60-65	55
California	70	65	65	55-65	55-65	25	25
Colorado	75	55-65	65	65
Connecticut	65	50-55	65	45	25-40
Delaware[1]	65	50-55	55	50		25	20
District of Columbia	-	55	-	-	-	25
Florida	70	60	65	60	55-60	30	10-20
Georgia[2]	70	55-65	65	55	-	30	25
Hawaii	60	50	45	45	45
Idaho	75	65	65	65
Illinois	65	55	55-65	55	55	30	20
Indiana	70	55	60	55	55
Iowa	70	55	65	55	45	25	20
Kansas	70	65	65-70	65	55	30
Kentucky	70[3]	55	55	55	55		20
Louisiana	70	60	65	55	45	25	20
Maine	65	55	55	55	50
Maryland	65	55-60	55	55			15-25
Massachusetts	65	55	55	55		30	20
Michigan[4]	70	70	55	55	55	25	25
Minnesota[5][6]	70	55-60	65	55-60	55	30
Mississippi	70	60-70	65	55		25
Missouri	70	55-65	65-70	55-65			20
State	Freeway (rural)	Freeway (urban)	4 lane (rural)	2 lane (rural)	County (rural)	Residential (urban)	School Zones
Montana	75	65	70	55-70	55-70	25	15
Nebraska[7]	75	60	65	60-65	50-55	25
Nevada	75	65	65-70	55-70	55-70	25	15, 25
New Hampshire	65	55	55	45	35	30
New Jersey[8][9]	65	55	55	50	50	25	20-25
New Mexico[10]	75	65	70	65	25-55	30	15
New York	65	55, 50nyc	55	55	55	30
North Carolina[11][12][13]	70	60	55	55		35	20
North Dakota[14][15]	75	55-75	70	65	50-65	25	15-25
Ohio[16]	65	55-65	55-65	55	55	25	20
Oklahoma	75t, 70	65	70	65	45	25	25
Oregon	65	55-60	55	55	55	25	20
Pennsylvania	65	55	65	55	40-45	25-35	15-20
Rhode Island[17]	65	55	55	50	-	25	20
South Carolina[18]	70	60	60	55	-	30
South Dakota	75	65	65-70	65	55	25-35
Tennessee	70	55	65-70	55	35-45	20-45	15-20
Texas	70-80	60	70-75	70-75	70hctra, 60	30	20
Utah	75	65	65	65		25-35	20
Vermont	65	55	55	50	50
Virginia[19]	65	55-60	55	55	55	25	20
Washington	70	60	65	65	50-55	25-40	20, 25
West Virginia	70	60	65	55
Wisconsin	65	55	65	55	55	25
Wyoming	75	60	65	65

Legend

• Freeway: Interstate highway or other state- or federally numbered road built to Interstate standards.
• 4 lane: State- or federally numbered 4 lane road not built to Interstate standards.
• 2 lane: State- or federally numbered 2 lane road.
• County: County-owned roads that are generally not numbered by the state.
• Residential: Residential streets.

Footnotes

• hctra: Harris County, Texas's toll road authority may post up to 70 mph limits on its tollway system.^[20]
• nyc: New York City freeway speed limit.
• t: Turnpike.

Other speed-related laws

State	Typical Fine	Recklessness threshold or enhanced penalty	Absolute/Prima facie	Ticket Dismissal Options	Point System
Texas	$1-$200[21] plus court fees. Doubled in active school zone or construction zone when workers are present.[22]	None[23]	Prima facie[24]	Defensive driving[25] (once per year) or deferred disposition[26] (restrictions vary, but generally at least 4 per year), but only valid if: Texas resident, speed < 25 mph above limit and < 95 mph, and not in construction zone where workers are present or active school zone.	Point system is annual surcharge only. No provision for license suspension.[27]
Rhode Island			Prima facie	One dismissal every 3 years for speed 14 mph or less over limit.[28]
Virginia	Up to $250[29] School zone: up to $250 additional[30] Work zone: up to $500[31] $100 civil penalty in certain towns[32]	20 mph over limit or over 80 mph[33] or "exceeds reasonable speed".[34]	Absolute[35]		Point system[36] leading to fines, suspension, and mandatory driver education.[37]

Definition of speeding

For record keeping purposes, speeding is defined by the U.S. federal government as (1) exceeding speed limits or (2) driving too fast for conditions.^[38] Speeds in excess of speed limits account for most speed-related traffic citations; generally, "driving too fast for conditions" tickets are issued only after an incident where the ticket issuer found tangible evidence of unreasonable speed, such as a crash.

A criticism of this definition of speeding is when speed limits are below the maximum safe speed, crashes that occur at speeds in excess of the limit can count as speed-related even when it is unclear whether the speed was unsafe.

Most speed-related crashes involve speed too fast for conditions. This includes conditions where speed under the effective limit may still be too fast, such as limited visibility or reduced road traction.^[39]

Variable speed limits offer some potential to reduce speed-related crashes. However, due to the high cost of implementation, they exist primarily on freeways. Furthermore, most speed-related crashes occur on local and collector roads.^[40] Speed-related crashes can also occur at speeds below 30 miles per hour; for example, truck rollovers on exit ramps.^[41]

Prima facie

Most states have absolute speed limits, meaning that a speed in excess of the limit is illegal per se. However, some states have prima facie speed limits.^[42] This offers motorists a valid defense to a speeding charge if it can be proven that the speed was in fact reasonable and prudent.

A successful prima facie defense is rare. Not only does the burden of proof rest upon the accused, a successful defense may involve expert witnesses or other expenses well in excess of the cost of a ticket. Furthermore, because prima facie defenses must be presented in a court, such a defense is difficult for out of town motorists.

Speed limits in Texas, Utah, and Rhode Island are prima facie. Some other states have a hybrid system: speed limits may be prima facie up to a certain speed or only on certain roads.

Federal speed limit controls (55 mph)

National Maximum Speed Law (1974)

For more details on this topic, see National Maximum Speed Law.

In response to the 1973 oil crisis, Congress enacted the National Maximum Speed Law that created the universal 55 mph speed limit.

The law was widely disregarded by motorists, even after the national maximum was increased to 65 mph in 1987 on certain roads. In 1995, the law was repealed, returning the choice of speed limit to each state.

2000s

Two prominent members of the United States Senate have speculated on reimposition of federal speed limit controls.

In 2006, Senator Hillary Clinton publicly supported reimposition of the 55 mph speed limit in a speech to the New York Press Club.^[43]

On July 3, 2008, U.S. Senator John Warner, R-VA, wrote a letter to Energy Secretary Samuel Bodman asking to look into what speed limit would provide optimum gasoline efficiency given current technology. He said he wants to know if the administration might support efforts in Congress to require a lower speed limit.^[44]

Political considerations in the U.S.

Political and fiscal considerations affect speed enforcement.

Traffic violations have proved to be a great source of income for many states. As a direct consequence, many state administrations have been reluctant to increase the speed limit on state roads. By keeping speed limits "unreasonably" low, the logical conclusion to this effort is that more motorists will appear to "speed". This gives law enforcement personnel the authority to issue traffic citations and thus improve the state's revenue. This policy has rarely been voiced or acknowledged. As a direct consequences of this, insurance companies have benefited as well. As motorists are charged with speeding violations their drivers licenses are assigned "violation points" (except for drivers licensed in South Dakota, where state law does not assign points for speeding violations). The more points accumulated on a license the more of a risk an insurance company will associate with the driver. This has a direct consequence of increasing insurance premiums thus resulting in greater revenue for the insurance company. Insurance companies rarely compete with each other as their premiums are determined by state guidelines. The same state of course, that sets the speed limits which results in a revenue generating enterprise between itself and the insurance companies. This association between the state and insurance companies is further solidified by the state insisting (through laws and policies) that "all" drivers have insurance policies with the insurance companies. If a driver cannot be covered under an insurance policy because of high risk the state will assume that high risk for a greater monetary amount; thus resulting in even more revenue generation for the state.^[45][46]

Noteworthy state distinctions

Alabama

Alabama recently set the speed limit for hazmat trucks to 55 mph.^[47]

California

In California, many speed limit signs are identified as "maximum speed", usually when the limit is 55 mph (90 km/h) or more.

California's "Basic Speed Law",^[48] of the California Vehicle Code, defines the maximum speed at which a car may travel as a "reasonable and prudent" speed, given road conditions. The numerical limit set by Caltrans engineers for speed limit signs, generally found on all non-controlled-access routes, is considered a presumptive maximum "reasonable and prudent" speed.

When the national maximum speed limit was enacted, California was forced to create a new legal signage category, "Maximum Speed", to indicate to drivers that the Basic Speed Law did not apply for speeds over the federally-mandated speed cap; rather, it would be a violation to exceed the fixed maximum speed indicated on the sign regardless of whether the driver's speed could be considered "reasonable and prudent".

A driver can receive a traffic citation for violating the Basic Speed Law even if their speed is below the posted "maximum speed limit" if road, weather or traffic conditions make that speed unsafe. However, because the Basic Speed Law establishes prima facie limits, not absolute ones, they can also defend against a citation for speeding "by competent evidence that the speed in excess of said limits did not constitute a violation of the basic speed law at the time, place and under the conditions then existing," per section 22351(b) of the California Vehicle Code.^[49]

As Attorney David W. Brown says in his book Fight Your Ticket & Win in California, "a person traveling over the speed limit--but less than the usual 65 mph maximum speed (55 mph for two-lane undivided highways)--isn't necessarily violating the law"^[50] and that "you can defend against a charge of violating the Basic Speed Law not only by showing you weren't exceeding the speed limit, but also by establishing that even if you were over the limit, your speed was nevertheless 'safe' under the circumstances." ^[51]

Rural speed limit on rural freeways, such as parts of I-5, I-8, I-10, I-15, I-40, U.S. 101 on the central coast, and SR 99 south of Madera and Fresno, have 70mph (110 km/h) speed limits. Because I-80 passes exclusively through urban and mountainous areas, its highest speed limit is only 65 mph.

In Los Angeles, the maximum speed limit within the downtown area is 55 MPH. This includes the entire length of the Pasadena Freeway between Pasadena and Downtown Los Angeles; and portions of the Hollywood, Santa Ana, Santa Monica and Harbor Freeways.

All of these freeways feature supplementary signage stating "AUTOS WITH TRAILERS/TRUCKS 55 MAXIMUM". Maximum truck/autos with trailers limit applies to trucks with 3 or more axles and all vehicles when towing. As of 2007, these signs are being replaced with signage stating "ALL VEHICLES WHILE TOWING 55 MAXIMUM".

The default limit on 2-lane roads is 55 mph. However, Caltrans or a local agency can post a speed of up to 65 mph after an engineering study.^[52]

In California, the Maximum Speed in school zones is 25 MPH, but is in effect only if children are present within that school zone.

Delaware

In Delaware, only two roads have a 65 mph (105 km/h) speed limit: I-495 and Delaware Route 1. Interstate 95 is posted at 55mph (90 km/h) and Interstate 295 is posted at 50mph (80 km/h).

All rural two-lane state-owned roads have 50 mph (80 km/h) speed limits, while all urban speed limits, regardless of location, is held at 25 mph (40 km/h) for two-lane roads and up to 35 mph (55 km/h) for four-lane roads. Four lane highways such as US 13 and US 113 are normally posted at 55mph.

School zones are 20 mph (30 km/h).

Florida

Florida raised its speed limit from the federally mandated 55 mph national limit (1974-1987) to 65 mph in 1987. In 1996, after the 1995 repeal of federal speed limit controls, Florida raised the speed limit to 70 mph on rural interstate highways, 65 mph on rural 4-lane highways (including US and State Highways), and 60 mph on rural 2-lane highways.

County roads are 55 to 60 mph depending on the jurisdiction.

Florida's minimum speed limit on interstate highways is now 50 mph in most 70 mph zones, up from the previous 40 mph minimum. In 55 mph, and 65 mph urban interstate zones, the minimum remains 40 mph.^{citation needed}

The State of Florida also does not impose a lower truck speed limit.

All interstate traffic is permitted to travel at the same speed.^{citation needed}

School zones in Florida are usually 10 mph to 20 mph. Most have flashing yellow lights activated during the times they are in effect as well as accompanying signs which post the times these reduced speed limits are effective. All are strictly enforced and carry an increased penalty for violations.

Florida typically does not post night speed limits, but there are a few exceptions. For the most part, these night time reduced speeds are located in wildlife preserves for such endangered species as the Florida panther and the key deer.

On some stretches of road where the speed limit is reduced at night, the daytime speed limit sign is non-reflective so at night, only the night limit is visible.

Hawaii

Hawaii was the last state to raise its maximum speed limit after the national maximum speed limit was repealed in 1995. In 2002, after public outcry after a controversial experiment with speed enforcement using road safety cameras, the state Department of Transportation raised the speed limit to 60 mph on two stretches of road:

• Interstate H-1 between Kapolei and Waipahu, and
• Interstate H-3 between the Tetsuo Harano Tunnels and the junction with H-1.^[53]

All other Interstates have a maximum speed limit of 55 mph, with the limit dropping to 50 mph in central Honolulu. Non-interstates generally have speed limits of 55 mph and in many cases much less.^[54]

Indiana

In Indiana speed limits on Interstate highways are usually 70 mph (110 km/h) for cars and 65 mph (105 km/h) for trucks, except in urban areas, where it is generally 55 mph (90 km/h) in city centers and 65 mph (105 km/h) cars/60 mph (95 km/h) trucks in suburban areas. Prior to July 5, 2005, all Interstate highways were 65 mph and below.

Most non-Interstate highways are 55 mph, but some rural four-lane divided highways are set at 60 mph. These limits often decrease to 30-45 mph (50-70 km/h) approaching urban areas, and within cities a speed limit of 20–30 mph (30–50 km/h) is not uncommon, though larger arterial roads within cities may reach as high as 45 mph (70 km/h).

Iowa

Iowa's rural Interstate speed limits are typically 70 mph (110 km/h), which no distinction made for trucks. Urban speed limits are usually set at 65 mph (105 km/h), with 55 mph speed limits set within cities, such as Interstate 235 in Des Moines. The Iowa DOT just recently increased the suburban speed limit on Interstate 235 to 60 mph, with 55 mph still posted for the downtown Des Moines area; 60 mph speed limits also exist on IA 58 and US 218 in Cedar Falls/Waterloo, and on Interstate 380 outside of downtown Cedar Rapids.

Non-Interstate divided highways are signed at 65 mph with speeds dropping to 55 mph in urban areas. Two lane rural state and county highways have a 55 mph speed limit.

Kentucky

In July 2007, Kentucky raised its rural freeway speed limits from 65 to 70.^[55] Kentucky does still have limits of 55 in some urban areas (I-71/75 near Cincinnati, I-64 and Interstate 264 in Louisville) with one 50 MPH area approaching the Sherman Minton Bridge crossing the Ohio River into Indiana on I-64.

Mississippi

A speed limit of 70 is only allowed on Mississippi's rural freeways; currently, only the Interstates (except I-110), U.S. Highway 78, and a portion of U.S. Highway 82 have speed limits of 70. A speed limit of 60 is typically used in urban areas where a higher speed limit might be used, but traffic or geometric conditions constitute a lower speed limit. Examples include I-20 in Vicksburg, Jackson, and Meridian, I-55 in Jackson, I-59 in Laurel (the speed limit drops to 40 mph) and Meridian, U.S. Highway 49 in Gulfport, U.S. Highway 61 at Tunica Resorts, US 78 in New Albany, and U.S. Highway 82 in Columbus.

Missouri

Missouri recently began a two-year experiment with variable speed limits along Interstate 270 around St. Louis. Digital signs have been erected along the highway as well as additional signs alerting drivers about the use of variable speed limits.

The limits will vary between 40 and 60 miles per hour, depending on traffic conditions, and could change by up to 5 mph every 5 minutes.

Montana

Reasonable and prudent era

In the years before 1974's 55 mph national maximum speed limit, and for three years after the 1995 65 mph repeal, Montana had a non-numeric "reasonable and prudent" speed limit during the daytime on most rural roads. Montana Code Annotated (MCA) Section 61-8-303 said "A person . . . shall drive the vehicle . . . at a rate of speed no greater than is reasonable and proper under the conditions existing at the point of operation . . . so as not to unduly or unreasonably endanger the life, limb, property, or other rights of a person entitled to the use of the street or highway."

Typical speed limit sign that one would see at the Montana state line from December 1995 to June 1999.

Montana law also specified a few numeric limits: a night speed limit, usually 55 or 65 mph (90–105 km/h), depending on road type; 25 mph (40 km/h) in urban districts and 35 mph (60 km/h) in construction zones.

The phrase "reasonable and prudent" is found in the language of most state speed laws. This allows prosecution under non-ideal conditions such as rain or snow when the speed limit would be imprudently fast.

No speed limit

On March 10, 1996,^[56] a Montana Patrolman issued a speed ticket to a driver traveling at 85 mph (140 km/h) on a stretch of State Highway 200. The 50 year-old driver was operating a 1996 Camaro with fewer than 10,000 miles (16,000 km) on the odometer. Although the officer gave no opinion as to what would have been a reasonable speed, the driver was convicted. The driver appealed to the Montana Supreme Court. The Court reversed the conviction in case No. 97-486 on December 23, 1998; it held that a law requiring drivers to drive at a non-numerical "reasonable and proper" speed "is so vague that it violates the Due Process Clause ... of the Montana Constitution".

75 mph speed limit

Despite this reversal, Montana's then Governor, Marc Racicot, did not convene an emergency session of the legislature. Montana technically had no speed limit whatsoever until June 1999, after the Montana legislature met in regular session and enacted a new law. The law's practical effect was to require numeric speed limits on all roads and disallow any speed limit higher than 75 mph (120 km/h).

Montana law still contains a section that says "a person shall operate a vehicle in a careful and prudent manner and at a reduced rate of speed no greater than is reasonable and prudent under the conditions existing at the point of operation, taking into account the amount and character of traffic, visibility, weather, and roadway conditions." However, this is a standard clause that appears in other state traffic codes and has the practical effect of requiring a speed lower than the speed limit where a lower speed is necessary to maintain a reasonable and prudent road manner.

New Hampshire

The highest limit is a maximum lawful speed limit of 65 mph (105 km/h), which can be found on the Interstate System, the Everett Turnpike, the New Hampshire Turnpike and the Spaulding Turnpike, in locations in which the highways are divided and have four or more lanes.

Provided that no hazard exists that requires lower speed, the speed of any vehicle not in excess of the limit is deemed to be prima facie lawful. The limit for "rural residential districts" and Class V highways outside the city or town compact is 35 mph. The limit for any "business or urban residence district" is 30 mph. School zones receive a 10 mph reduction in the limit 45 minutes before and after the beginning and end of a school day. The speed limit for a road work or construction area is 10 mph lower than the normal speed limit, but not more than 45 mph, when work is in progress. The speed limit for all other locations is 55 mph. The minimum limit that a speed can be set in a rural or urban district is 25 mph.

New Jersey

The common speed limit on a divided highway in New Jersey is 65 mph. Highways such as the New Jersey Turnpike (which uses variable electronic speed limit signs near Newark) south of Exit 12, the Atlantic City Expressway (north of the Garden State Parkway), the Garden State Parkway (north of Exit 163 in Paramus and south of the Sayreville toll barrier), NJ Route 55, I-80, I-287, and I-78 have 65 mph limits where speeding fines are doubled. Residential roads have 25 mph speed limits. Two-lane rural highways and two-lane county roads generally have 45 and 50 mph limits.

New Mexico

Prior to the National Maximum Speed Law in 1974, the speed limit on rural Interstates was 75 miles per hour in the daytime, 70mph nighttime. In May of 1996 legislation enacted by Governor Gary E. Johnson raised the absolute speed limit^[57] in New Mexico to 75mph. Signs were posted on the vast majority of the mileage of Interstate routes to that effect. Before the end of federal speed related legislation the maximum speed limit was 65mph on Interstate routes and 55mph elsewhere.

Today New Mexico has six major freeway facilities which include three lengthy Interstate routes. Parts of US70 between Las Cruces and Alamogordo (a divided highway and freeway near Las Cruces) also have the posted 75mph limit. I10 has a posted 70mph speed limit from the Texas border to Las Cruces. I25 has a posted 70mph limit from Bernalillo to Albuquerque. And I40 has a posted 65mph speed limit on its Eastern approach to the same city through Tijeras pass. The US84/285 freeway between Pojoaque and Santa Fe has a posted 65mph limit. A short freeway section of NM423 has a posted 60mph limit, while most of I25 and I40 have posted 65mph speed limits within Albuquerque, except for the former which has a 1.5 mile posted 55mph stretch.

Other state maintained roads have posted speed limits of up to 70mph, although thirty mph to 65mph is normal. Many rural two lane highways still have posted 55mph limits for a variety of reasons. There are two other statutory^[58] speed limits in New Mexico which are often altered, especially on urban arterials or even city or countywide: thirty miles per hour in a "buisness or residence district" and fifteen miles per hour near schools at certain times. For example, in Albuquerque the default speed limit is thirty miles per hour as per state law, but many streets have a different posted speed limit. Some school zones there have twenty mile per hour posted speed limits. The city of Santa Fe's default speed limit is twenty five miles per hour. Although there are no signs to make drivers aware of the altered limit, the limit is posted on most roads where it applies. The county of Los Alamos alters the urban default and absolute speed limits to twenty five miles per hour and 50mph respectively, but posts signs at county lines.

There is a left lane minimum speed limit on roads with 75mph speed limits of 65mph. This is occasionally posted on steep grades as a reminder, "slower traffic keep right" is also posted. State law reserves the left lane of two lanes for passing. There are advisory speed limits for some roads during poor weather. Speeding fines are doubled in work zones, signs are often posted stating this.

New York

A standard-style New York State speed sign indicating the 'State Speed Limit'.

The highest speed limit is 65 mph (105 km/h), which is found on most of the New York State Thruway and other rural Interstate highways. The State Speed Limit (a blanket or default speed limit for rural roads) is 55 mph (90 km/h), which is also the highest a non-expressway or parkway highway may have. Signs in New York thus read "State Speed Limit" when the speed limit is 55. The theme is followed, and many signs read "Area Speed Limit", "Town Speed Limit", "City Speed Limit" or "Village Speed Limit" with varying speeds shown below. In New York State, the default speed limit on any road not marked with a speed limit sign is 55 mph (unless local restrictions are stricter).^[59] New York City and some other urbanized areas have a default speed limit of 30 mph (50 km/h) except where otherwise posted. The highest speed limit on expressways and parkways in New York City is 50 mph (80 km/h).

Governor George Pataki signed legislation in September 2003 that enables NYSDOT and NYSTA to raise speed limits to 65 mph on its roads that meet established design and safety standards. This legislation became active in March 2004, and has been used on over 100 miles worth of highway. An example of this is a 3-mile section of NY Route 7 (locally known as "Alternate Route 7") which connects Exit 7 of Interstate 87 (the Adirondack Northway) with Interstate 787, the main highway into the city of Albany, NY. Prior to the new law, consent of the state legislature was necessary to enact a 65 mph speed limit, a process that could take months or years. In fact, New York was one of the last states in the United States to enable speed limits above 55 mph on any roads.

North Carolina

Along two lane rural primary and secondary roads outside municipal limits, the statutory speed limit is 55mph unless otherwise posted. Inside the municipal limits, the statutory speed limit is 35mph unless otherwise posted. The downtown statutory speed limit is 20mph unless otherwise posted. Reduced Speed Ahead signage is the norm whenever the speed limit drops at any level. Three to eight lane boulevards with or without center turn lanes, range from 35mph to 50mph within municipal limits statewide.

School speed limits are generally dropped 10mph below the original speed limit during open school hours of arrivals and departures. A school speed limit would be posted when entering the school zone. Also, the default speed limit is posted after leaving the school zone. A school speed limit cannot be below 20mph.

Military bases are 50mph maximum. The exceptions are any numbered highways.

The state park speed limit is 25mph unless otherwise posted. These are not limited to places like Hanging Rock State Park and Mount Mitchell State Park.

The Blue Ridge Parkway is posted at 45mph however, there are occasional 35mph stretches. The National Park Service is responsible for highway maintenance and speed enforcement.

The county governments of North Carolina do not have any control over speed limits except municipalities. The exception of this rule are city-county governments like Charlotte.

60mph speed limits are growing in popularity into replacing 55mph boulevard and expressway segments throughout the state. The boulevard speed limit changes go against the NCDOT rationale behind signing 60mph speed limits along only freeway and expressway segments. As of June 1, 2008, some examples of the affected boulevards are US 17 north of Elizabeth City, US 74 east of Wadesboro and NC 11 in Pitt County. Some examples of the affected expressways are US 1 in northeastern Moore County, US 17 on bypass routes in Brunswick County, US 74 east of I-95, US 117 in Wayne County and US 220 in Rockingham County.

North Dakota

The highest speed limit found in North Dakota is 75 mph, which can be found on Interstates 29 and 94. Rural four-lane divided highways are 70 mph. Rural 2-Lane Federally, and State Highways is 65 mph. Four-lane divided, Federally, and State Highways pass through cities is 25-65 mph. Highest speed limit for county roads can be found on portions on Ward County CR 23 and Burleigh County CR 10. Certain major county roads are generally 50-55 mph for Statutory cars and 30-45 mph for trucks. 55 mph for unposted speed limits on other county roads. Speed limits on surface streets range from 30-40 mph. Residential streets are generally 15-25 mph. School zones are 15-25 mph.

Ohio

The maximum speed limit found on highways in Ohio is 65 miles per hour. Truck maximum speed applied to all vehicles with an empty vehicle weight greater than 8,000 pounds and all non-commercial buses.^[16]

The truck maximum speed is typically 55 miles per hour, 10 miles per hour lower than which is allowed for smaller vehicles. The only road in Ohio that allows trucks to exceed 55 mph is the Ohio Turnpike, which doesn't post a lower truck limit, allowing them to travel at 65 mph, in an effort to divert truck traffic off of the non-toll US-20 roadway.

Historically, Ohio had night speed limits of 50 miles per hour on Interstate highways.^[60] Additionally, certain highways had speed limits as high as 75 miles per hour.^[61]

Oklahoma

In Oklahoma, the maximum speed limit is 75 miles per hour on turnpikes and 70 mph on all other freeways. Most other rural highways have a 65 mph speed limit (although some rural divided highways have a 70 mph limit).

Oregon

A standard-style Oregon speed sign removing the word "limit".

Up until 2002, Oregon state law required that all speed limit signs remove the word limit from their display. The reasoning behind this is unknown but the practice has been known to produce some unusual number fonts. The spacing between and appearance of the numbers on the signs vary greatly depending on which jurisdiction made the sign. In 2002, the Oregon Department of Transportation permitted the inclusion of the word "limit" on speed signs and left it up to local government agencies to decide on whether "limit"-branded signs would be installed. Most have chosen not to change over with a few exceptions to the rule. Speed Limit 60 signs can be found on Interstate 5 through Salem and on Interstate 84 through east Portland. The City of Beaverton has been the most liberal in retrofitting the standard-form Speed Limit sign, presumably because the "SPEED" signs do not use a standard number font and are likely more expensive to make. Whenever a "Speed" sign is damaged or vandalized in Beaverton city limits, a "Speed Limit" sign takes its place.

Throughout the late 1990s the Oregon state legislature passed multiple bills that would have raised the speed limit to 75 miles per hour on rural Interstate highways and up to 70 mph on certain rural two lane highways in the eastern portions of the state. Each year Governor John Kitzhaber vetoed the bill. In 2003, the Oregon state legislature passed a bill that would have raised the maximum permissible speed limit on Interstate highways to 70 mph for cars with a 5 mph differential for trucks, up from the previous 65 mph limit for cars with a 10 mph differential, this bill was signed into law by then newly elected Governor Ted Kulongoski. In 2004 the Oregon Department of Transportation decided to not implement the increase out of concerns that it would not be safe to have trucks traveling at 65 mph. Prior to the National Maximum Speed Law, the speed limit on Oregon interstates could be as high as 75 mph. Oregon remains the only state west of the Mississippi River to have a maximum state speed limit that is under 70 mph.

In 2004, a law was passed revising Oregon's school speed limit laws. In school zones, on roads with speed limits of 30 mph or below, drivers were required to slow to the school speed limit of 20 mph 24 hours a day, 365 days a year, regardless of whether or not children were present. This replaced most 'when children are present' placards. If the speed limit was 35 mph or higher, the school zone limit would be imposed either by flashing yellow lights or a placard denoting times and days of the week when the limit was in effect. The at-all-times rule was highly unpopular with motorists and was widely ignored. In fact, it is likely that this law has led to a reduced acceptance of school speed limits, regardless of how and when they are in effect^{citation needed}. In 2006, the law was revised again, taking away the 'at all times' requirement and replacing it with a time-of-day system (usually school days, 7 a.m. to 5 p.m.). School crossings with flashing yellow lights remain.

Pennsylvania

In 1940, when the Pennsylvania Turnpike was opened between Irwin and Carlisle, the entire 110 mile highway did not have a speed limit, similar to that of the German Autobahns. In 1941, a speed limit of 70 mph (110 km/h) was established, only to be reduced to 35 mph (55 km/h) during the war years (1942–45). After WWII, the limit was raised to 70 mph on the four-lane sections, with the two-lane tunnels having 50 mph (80 km/h) for cars and 40 mph (65 km/h) for trucks. Prior to the 1974 federal speed limit law, all Interstates and the Turnpike had a 65 mph (105 km/h) speed limit on rural stretches and 60 mph (100 km/h) speed limit in urban areas.

In 1995, the state raised the speed limit on rural stretches of Interstate Highways and the Pennsylvania Turnpike system to 65 mph (105 km/h), with urban area having a 55 mph (90 km/h) limit. In 1997, PennDOT raised the speed limit to some rural non-Interstate highway bypasses to 65 mph (105 km/h). In 2005, with the change in the designation of "urban zones" in the state, the entire lengths of both the Pennsylvania Turnpike's east-west mainline and Northeast Extension were given 65 mph (105 km/h) limits, except at the tunnels and through the very winding 5.5 mile (9 km) eastern approach to the Allegheny Mountain Tunnel.

On non-freeway roads, speed limits are generally held at 65 mph (105 km/h) for rural four-lane roads, 55 mph (90 km/h) for rural two-lane roads, 45 mph (70 km/h) for urban four lane and state-owned two lane roads, 35 mph (55 km/h) for major roadways in residential areas, 25 mph (40 km/h) for most municipal residential streets, including main north–south and east–west roads in county seats, and 15-20 mph (25 km/h) for school zones during school arrival and departure times only. It is also only in effect on days that particular school is in session. Many schools have signs that blink when the school speed limit is in effect. The speed is determined by the school's proximity to the road. There is no reduced school speed on divided highways, even if the school sits right beside the highway or interstate.

Puerto Rico

The US territory of Puerto Rico regulates and posts speed limits in miles per hour, although highway signage for distances are in kilometers. Toll Autopistas can have speed limits up to 65 mph, while other freeways have speed limits up to 60 mph.

South Dakota

Shortly after the December 1995 repeal of the 65/55 mph national maximum speed limit, South Dakota raised its general rural speed limits to 75 mph on freeways and 65 mph on other roads. Almost a decade after posting the 75 mph limit, average speeds on South Dakotan rural freeways remain at or below the speed limit.^[62] South Dakota also has the distinction of being the only state that does not assign points to one's driving record for speeding convictions.

Texas

Typical Texas rural speed limit sign. Note the black backgrounded 65 mph night speed limit sign, common on Texas roads. (Few other states have widespread night speed limits.) This sign is on southbound U.S. 69/96/287 just north of Beaumont.

Texas is the only state that does not prescribe a speed limit for each road type. Any rural road—two lane, four lane, Interstate, or otherwise—that is numbered by the state or federal government has a 70 mph (110 km/h) statutory limit.^[63] The law generally allows changing the 70 mph limit only if a study recommends a different limit.^[64]

75 mph and 80 mph limits

Texas statutorily allows the Texas Department of Transportation to post 75 mph (120 km/h) speed limits in counties with average populations of fewer than 15 people per square mile.^[64] The same statute also allows 80 mph (130 km/h) speed limits on I-10 and I-20 in certain counties named in the statute, all of which happen to be rural, in west Texas, and have a low population density. Daytime truck limits are capped at 70 mph, and nighttime speed limits remain 65 mph for all vehicles. (Nothing prohibits nighttime speed limits from being raised to 70 mph, but the Department has not elected to do so.)

In 2001, the Texas Legislature allowed the Texas Department of Transportation to post 75 mph (120 km/h) speed limits in counties with fewer than 10 people per square mile.^[65] This has the practical effect of only allowing 75 mph speed limits in the most sparsely populated counties, all of which are generally well west of a line stretching from San Antonio to Odessa. In 2005, the Texas Legislature revised this law, allowing 80 mph (130 km/h) limits on I-10 and I-20 in certain rural counties in west Texas. This bill also revised the eligibility for 75 mph speed limits: now eligible counties can have up to 15 persons per square mile. This did not substantially increase the miles of roadway eligible for higher limits, however.^[66]

Texas Legislator Pete Gallego unveiling a new 80 mph speed limit sign on Interstate 10 near Fort Stockton, Texas.

On May 25, 2006, the Texas Transportation Commission has approved 80 mph speed limits,^[67] and signs are posted.

In a widely printed Associated Press story about the 80 mph speed limit,^[68] Texas is incorrectly reported as having legalized 75 mph limits in 1999. In fact, the bill that would have done this, HB 3328^[69] by Pete Gallego, died in conference committee just before the Texas Legislature's session ended. This bill would have, in effect, set 75 mph as the statutory speed limit on any rural road numbered by the state or federal government, and it would have enacted—not simply allowed—an 80 mph speed limit on I-10 and I-20 in any county with fewer than 25,000 residents.

While Texas's 80 mph limit is higher than any limit authorized by another state, it is equivalent to the 130 km/h recommended speed on the Autobahn and the actual 130 km/h rural expressway speed limit in thirteen other European countries.^[70]

Because Texas law allows 75 mph speed limits on any road numbered by the state or federal government, it is the only state with 75 mph limits on two-lane roads. Several west Texas two-lane roads carry 75 mph limits, including portions of US 90^[71] No other state has a limit higher than 70 mph on any two-lane road.

85 mph limits

The legislation creating the Trans-Texas Corridor allows speed limits of up to 85 mph (140 km/h)^[72] on roads built under the program. However, no such roads have been built as of January 2008. The language of the statute does not prohibit the Texas Transportation Commission from raising the truck speed limit or the night speed limit on these roads.

Night speed limits

While the "basic rule", which requires drivers to drive a "reasonable and prudent" speed at all times, is usually relied upon to regulate proper night speed reductions, night speed limits generally may be established on roads where safety problems require a speed lower than what is self-selected by drivers.

Texas

Texas is the only state with a universal, arbitrary night speed limit. Texas statutorily prescribes:

• a blanket 65 mph (105 km/h) night speed limit on roads with a speed limit of at least 70 mph (110 km/h).^[63] While the Texas Department of Transportation has the power to lower this night speed limit or raise it to 70 mph, it in fact rarely does, so nearly every 70 mph or higher speed limit sign has an accompanying 65 mph night speed limit sign.
• a 55 mph night speed limit for trucks on farm to market roads, complementing the statutory 60 mph truck day limit on these roads. (This is a holdover from Texas's truck speed limits.)
• a 55 mph night speed limit on county roads (except for Harris County Toll Road Authority-owned toll freeways).

Other states

North Dakota, Montana,^[73] and Oklahoma^{citation needed} also have night speed limits, but they are only generally applicable to rural, non-Interstate-class roads.

Minnesota once had a night speed limit on sections of MN 61 due to the danger of rocks falling off the cliffs alongside the road. Tunnels constructed between Two Harbors and Silver Bay bypassing the dangerous areas along cliffs and subsequent widening of the highway in other locations have made the night speed limit unnecessary.

Environmental speed limits

Texas

55 mph speed limit signs photographed on August 20, 2002. These signs were on southbound I-45 at the north border of Montgomery County. Immediately before this point, the speed limit was 70 mph. These were part of an unpopular 55 mph speed limit cap in the Houston–Galveston area.

Same location as prior picture with the more recent 65 mph speed limit, photographed on August 4, 2005.

Texas is the first state to lower speed limits for air quality reasons. In roughly a 50 mile (80 km) radius of the Houston–Galveston and Dallas–Ft. Worth regions, the Texas Commission on Environmental Quality convinced^[74] the Texas Department of Transportation to reduce the speed limit on all roads with 70 mph (110 km/h) or 65 mph (105 km/h) speed limits by 5 mph.^[75] This was instituted as part of a plan to reduce smog-forming emissions in areas out of compliance with the federal Clean Air Act.^[76]

Initial studies found that lower speed limits could bring the areas roughly 1.5% closer to compliance.^[77] However, follow up studies found that the actual reduction is far less:

1. The emissions modeling software initially used, MOBILE 5a, overestimated the emissions contribution of speed limit reductions. Rerunning the models with the next generation software, MOBILE 6, produced dramatically lower emissions reductions.
2. Speed checks in the Dallas area performed 1 year after implementation of speed limit reductions show that actual speed reductions are only about 1.6 mph, a fraction of the anticipated 10% (5.5 mph) speed reduction.

With both of these facts combined, it is possible that the speed limit reductions only provide a thousandth of the total emissions reductions necessary for Clean Air Act compliance.^[78]

In mid-2002, all speed limits in the Houston–Galveston area were capped at 55 mph (90 km/h).^[79] Facing immense opposition,^[80][81] poor compliance,^[82] and the finding that lowered speed limits produced only a fraction of the originally estimated emissions reductions,^[83] the TCEQ relented and reverted to the 5 mph reduction scheme.^[84]

In 2003, the Texas Legislature prospectively banned environmental speed limits effective September 1, 2003. The wording of the bill allows environmental speed limits already in place to remain indefinitely; no new miles of roadway may be subjected to environmental speed limits, however.^[85]

This law has allowed interesting inconsistencies. Generally, all primary arterial roadways within the inner loops of Texas cities have speed limits of 60 mph (95 km/h) or lower, so they were not subjected to environmental speed limits. Arterial roads between the inner loop and the outer loop generally have 65 mph (105 km/h) limits, and arterial roads outside the outer loop generally have 70 mph (110 km/h) limits.^{citation needed} (Note that this is only the typical pattern and is not prescribed by law.) In at least one case—TX 121 between I-35W and I-820 in Ft. Worth—the speed limit rises from 60 mph to 65 mph as one crosses IH-820 approaching downtown,^{citation needed} contravening the standard.

Tennessee

Following the example of Texas, Tennessee has used environmental speed limits as part of pollution control efforts in Shelby, Hamilton, Sullivan, Knox, Blount, Jefferson, Roane, Loudon, Anderson, and Sevier counties, lowering the maximum truck speed limit to 55 mph (89 km/h) and the maximum car speed limit to 65 mph (105 km/h) within portions of these counties.^[86][87]

Delaware

Interstate 495, which forms a bypass around Wilmington, Delaware, features changeable speed limit signs for environmental purposes. These signs typically display a 65 mph speed limit, but this limit changes to 55 mph on days when air quality is a concern.

Minimum speed limits

In addition to the legally defined maximum speed, minimum speeds may be required. There is little evidence to suggest they are enforced.^{citation needed}

• Connecticut limited-access divided highways have a minimum speed of 40 mph (65 km/h),^[88] but they are not always posted.

• Florida interstate highways have minimum speeds of 40 to 50 mph.^{citation needed}

• Hawaii has a minimum speed posted along much of Interstate H-1 of only 10 mph below the speed limit. The minimum speed is usually 45 mph when the speed limit is 55, and 40 mph when the speed limit is 50.

• Illinois interstate highways are usually posted with both minimum and maximum speed limits, except in some urban areas, particularly Chicago. The minimum speed is almost always 45 mph.^{citation needed}

• Iowa rural interstates have a maximum speed limit of 70 mph and a minimum speed limit of 40 mph, and U.S. Highway 20 between Interstate 35 and Dubuque also has a 40 mph minimum speed, even though its interstate-quality road is signed at a 65 mph maximum. Other four-lane divided rural highways are signed at 65 mph, with no minimum speed (with the purpose of allowing slow-moving farm vehicles to use the road as well).

• Michigan freeways are usually posted with both minimum and maximum speeds. The minimum speed is currently 55 mph for all vehicles, despite a maximum speed limit of 60 mph for trucks — effectively permitting trucks only a 5-mph range of legal speeds.^[4]

• Mississippi has a minimum speed of 30 mph on four-lane U.S. highways when no hazard exists. Strangely, there is no law for the minimum speed of the state's growing number of four-lane state highways. The minimum is 40 mph on Interstate highways and on 4 lane U.S. designated highways which have a 70 mph speed limit, but this minimum shall be posted.^[89] In 2004, Mississippi posted minimum speed limits (40 mph) on all rural Interstates, but this minimum speed limit was already state law before the widespread posting.

• Missouri and Minnesota interstate highways have minimum speed of 40 mph.^[90]