Speed limits in the United States
Speed limits in the United States are set by each state or territory. States also allowed counties and municipalities, to enact typically lower limits. Highway speed limits can range from an urban low of 25 mph (40 km/h) to a rural high of 85 mph (137 km/h). Speed limits are typically posted in increments of five miles per hour (8 km/h). Some states have lower limits for trucks and at night, and occasionally there are minimum speed limits.
The highest speed limits are generally 70 mph (113 km/h) on the West Coast and the inland eastern states, 75–80 mph (121–129 km/h) in inland western states, along with Arkansas and Louisiana, and 65–70 mph (105–113 km/h) on the Eastern Seaboard. Alaska, Connecticut, Delaware, Massachusetts, New Jersey, New York, Puerto Rico, Rhode Island, and Vermont have a maximum limit of 65 mph (105 km/h), and Hawaii has a maximum limit of 60 mph (97 km/h). The District of Columbia and the U.S. Virgin Islands have a maximum speed limit of 55 mph (89 km/h). Guam, the Northern Mariana Islands and American Samoa have speed limits of 45 mph (72 km/h). Two territories in the U.S. Minor Outlying Islands have their own speed limits: 40 mph (64 km/h) in Wake Island, and 15 mph (24 km/h) in Midway Atoll.^{[1]}^{[2]} Unusual for any state east of the Mississippi River, much of I95 in Maine north of Bangor allows up to 75 mph (121 km/h), and the same is true for up to 600 miles of freeways in Michigan. Portions of the Idaho, Montana, Nevada, South Dakota, Texas, Utah, and Wyoming road networks have 80 mph (129 km/h) posted limits. The highest posted speed limit in the country is 85 mph (137 km/h) and can be found only on the Texas State Highway 130.
For 13 years (January 1974^{[3]}–April 1987^{[4]}^{[5]}), federal law withheld Federal highway trust funds to states that had speed limits above 55 mph (89 km/h).^{[4]} From April 1987 through December 8, 1995, an amended federal law disincentivized speed limits above 65 mph (105 km/h).
Contents
Overview
Speed limits
This table contains the most usual posted daytime speed limits, in miles per hour, on typical roads in each category. The values shown are not necessarily the fastest or slowest. They usually indicate, but not always, statutory speed limits. Some states and territories have lower truck speed limits applicable to heavy trucks. If present, they are usually only on freeways or other highspeed roadways. Washington allows for speeds up to 75 mph (121 km/h), but the highest posted signs are 70 mph (110 km/h). Mississippi allows speeds up to 80 mph (129 km/h) on toll roads, but no such roads exist. Oklahoma removed the maximum speed of 75 from its laws, though no road has been posted higher than 75.
Legend:  

Freeway: Interstate Highway or other state or U.S. Route built to Interstate standards. Divided rural: State or U.S. route, generally with four or more lanes, not built to Interstate standards, but with a median or other divider separating directions of travel. Undivided rural: County, State, or U.S. route, generally with two to four lanes, with no separator between directions of travel. Residential Street/residential: Residential streets, business districts, or School zones. 




State or territory  Freeway (rural)  Freeway (trucks)  Freeway (urban)  Divided (rural)  Undivided (rural)  Residential 

Alabama^{[6]}^{[7]}  70 mph (113 km/h)  55–70 mph (89–113 km/h)  65 mph (105 km/h)  45–65 mph (72–105 km/h)  20–25 mph (32–40 km/h)  
Alaska  65 mph (105 km/h)  55–65 mph (89–105 km/h)  55–65 mph (89–105 km/h)  45–65 mph (72–105 km/h)  20–25 mph (32–40 km/h)  
American Samoa^{[8]}  no freeways in American Samoa  45 mph (72 km/h)  30–45 mph (48–72 km/h)  20 mph (32 km/h)  
Arizona^{[9]}  65–75 mph (105–121 km/h)  55–65 mph (89–105 km/h)  55–65 mph (89–105 km/h)  45–65 mph (72–105 km/h)  20–25 mph (32–40 km/h)  
Arkansas  70–75 mph (113–121 km/h)  70 mph (113 km/h)  60–65 mph (97–105 km/h)  65 mph (105 km/h)  55–65 mph (89–105 km/h)  30 mph (48 km/h) 
California  65–70 mph (105–113 km/h)  55 mph (89 km/h)  50–65 mph (80–105 km/h)  65 mph (105 km/h)^{[10]}  55–65 mph (89–105 km/h)  25–30 mph (40–48 km/h) 
Colorado  65–75 mph (105–121 km/h)  55–75 mph (89–121 km/h)  55–65 mph (89–105 km/h)  55–65 mph (89–105 km/h)  20–35 mph (32–56 km/h)  
Connecticut  65 mph (105 km/h)  45–55 mph (72–89 km/h)  50–55 mph (80–89 km/h)  45–50 mph (72–80 km/h)  20–40 mph (32–64 km/h)  
Delaware^{[11]}  65 mph (105 km/h)  50–65 mph (80–105 km/h)  45–60^{[12]} mph (72–97 km/h)  35–50 mph (56–80 km/h)  20–35 mph (32–56 km/h)  
District of Columbia^{[13]}  no rural freeways in D.C.  55 mph (89 km/h)  no rural roads in D.C.  25 mph (40 km/h)  
Florida^{[14]}  70 mph (113 km/h)  45–70 mph (72–113 km/h)  55–65 mph (89–105 km/h)  55–60 mph (89–97 km/h)  20–50 mph (32–80 km/h)  
Georgia^{[15]}  70 mph (113 km/h)  55–70 mph (89–113 km/h)  65 mph (105 km/h)  55 mph (89 km/h)  25–45 mph (40–72 km/h)  
Guam^{[16]}^{[17]}^{[18]}  no freeways in Guam  45 mph (72 km/h)  35–45 mph (56–72 km/h)  35 mph (56 km/h)  
Hawaii  55–60 mph (89–97 km/h)  35–50 mph (56–80 km/h)  45–55 mph (72–89 km/h)  45–60 mph (72–97 km/h)  25 mph (40 km/h)  
Idaho  70–80 mph (113–129 km/h)  70 mph (113 km/h)  60–65 mph (97–105 km/h)  65–70 mph (105–113 km/h)  55–70 mph (89–113 km/h)  25–35 mph (40–56 km/h) 
Illinois  70 mph (113 km/h)  45–70 mph (72–113 km/h)  65 mph (105 km/h)  55 mph (89 km/h)  20–30 mph (32–48 km/h)  
Indiana  70 mph (113 km/h)  65 mph (105 km/h)  50–70 mph (80–113 km/h)  55–60 mph (89–97 km/h)  50–55 mph (80–89 km/h)  20–30 mph (32–48 km/h) 
Iowa  70 mph (113 km/h)  55–65 mph (89–105 km/h)  65 mph (105 km/h)  45–55 mph (72–89 km/h)  25 mph (40 km/h)  
Kansas  75 mph (121 km/h)  60–75 mph (97–121 km/h)  65–70 mph (105–113 km/h)  55–65 mph (89–105 km/h)  20–30 mph (32–48 km/h)  
Kentucky^{[19]}  70 mph (113 km/h)  55–70 mph (89–113 km/h)  65 mph (105 km/h)  55 mph (89 km/h)  25–45 mph (40–72 km/h)  
Louisiana^{[20]}  70–75 mph (113–121 km/h)  50–70 mph (80–113 km/h)  55–65 mph (89–105 km/h)  45–55 mph (72–89 km/h)  20–45 mph (32–72 km/h)  
Maine  70–75 mph (113–121 km/h)  50–65 mph (80–105 km/h)  45–55 mph (72–89 km/h)  45–55 mph (72–89 km/h)  25 mph (40 km/h)  
Maryland  65–70 mph (105–113 km/h)  40–65 mph (64–105 km/h)  55 mph (89 km/h)  50–55 mph (80–89 km/h)  20–25 mph (32–40 km/h)  
Massachusetts  65 mph (105 km/h)  45–65 mph (72–105 km/h)  45–55 mph (72–89 km/h)  45–55 mph (72–89 km/h)  20–30 mph (32–48 km/h)  
Michigan^{[21]}  70–75 mph (113–121 km/h)^{[22]}  65 mph (105 km/h)  55–70 mph (89–113 km/h)  55–65 mph (89–105 km/h)  55–65 mph (89–105 km/h)^{[22]}  25 mph (40 km/h) 
Midway Atoll^{[2]}  no freeways in the Midway Islands  15 mph (24 km/h)  
Minnesota^{[23]}^{[24]}  70 mph (113 km/h)  45–60 mph (72–97 km/h)  60–65 mph (97–105 km/h)  55–60 mph (89–97 km/h)  30 mph (48 km/h)  
Mississippi  70 mph (113 km/h)  55–70 mph (89–113 km/h)  65 mph (105 km/h)  55 mph (89 km/h)  25 mph (40 km/h)  
Missouri  70 mph (113 km/h)  45–70 mph (72–113 km/h)  60–70 mph (97–113 km/h)  55–65 mph (89–105 km/h)  25–40 mph (40–64 km/h)  
Montana  75–80 mph (121–129 km/h)  65 mph (105 km/h)  65 mph (105 km/h)  65–70 mph (105–113 km/h)  55–70 mph (89–113 km/h)  20–25 mph (32–40 km/h) 
Nebraska^{[25]}  75 mph (121 km/h)  55–65 mph (89–105 km/h)  65–70 mph (105–113 km/h)  55–70 mph (89–113 km/h)  25 mph (40 km/h)  
Nevada  70–80 mph (113–129 km/h)^{[26]}^{[27]}^{[28]}  55–65 mph (89–105 km/h)  65–75 mph (105–121 km/h)  55–75 mph (89–121 km/h)  20–30 mph (32–48 km/h)  
New Hampshire  65–70 mph (105–113 km/h)  50–65 mph (80–105 km/h)  55 mph (89 km/h)  35–55 mph (56–89 km/h)  20–30 mph (32–48 km/h)  
New Jersey^{[29]}^{[30]}  65 mph (105 km/h)  50–65 mph (80–105 km/h)  55 mph (89 km/h)  30–55 mph (48–89 km/h)  20–35 mph (32–56 km/h)  
New Mexico^{[31]}  75 mph (121 km/h)  55–75 mph (89–121 km/h)  55–75 mph (89–121 km/h)  55–70 mph (89–113 km/h)  20–55 mph (32–89 km/h)  
New York^{[32]}  65 mph (105 km/h)  35–55 mph (56–89 km/h)  45–55 mph (72–89 km/h)  35–55 mph (56–89 km/h)  20–45 mph (32–72 km/h)  
North Carolina^{[33]}^{[34]}  65–70 mph (105–113 km/h)  50–70 mph (80–113 km/h)  55–60 mph (89–97 km/h)^{[35]}  55 mph (89 km/h)  20–35 mph (32–56 km/h)  
North Dakota^{[36]}^{[37]}  75 mph (121 km/h)  55–75 mph (89–121 km/h)  55–70 mph (89–113 km/h) ^{[38]}  55–70 mph (89–113 km/h)  20–55 mph (32–89 km/h)^{[38]}  
Northern Mariana Islands^{[39]}  no freeways in Northern Mariana Islands  45 mph (72 km/h)  25 mph (40 km/h)  
Ohio^{[40]}^{[41]}  70 mph (113 km/h)  50–70 mph (80–113 km/h)  55–70 mph (89–113 km/h)^{[42]}^{[43]}  45–70 mph (72–113 km/h)  20–35 mph (32–56 km/h)  
Oklahoma  70 mph (113 km/h) (75 mph (121 km/h) turnpikes)  55–65 mph (89–105 km/h)  65–70 mph (105–113 km/h)  55–65 mph (89–105 km/h)  25 mph (40 km/h)  
Oregon  6570 mph
(105–113 km/h) 
60–65 mph (97–105 km/h)  50–60 mph (80–97 km/h)  55–70 mph (89–113 km/h)  55–70 mph (89–113 km/h)  20–25 mph (32–40 km/h) 
Pennsylvania  65–70 mph (105–113 km/h)  40–70 mph (64–113 km/h)  55 mph (89 km/h)  40–55 mph (64–89 km/h)  20–35 mph (32–56 km/h)  
Puerto Rico^{[44]}  60–70 mph (97–113 km/h)  55 mph (89 km/h)  50–55 mph (80–89 km/h)  55 mph (89 km/h)  45–55 mph (72–89 km/h)  25–35 mph (40–56 km/h) 
Rhode Island^{[45]}  65 mph (105 km/h)  50–55 mph (80–89 km/h)  55 mph (89 km/h)  50 mph (80 km/h)  20–25 mph (32–40 km/h)  
South Carolina^{[46]}  70 mph (113 km/h)  55–70 mph (89–113 km/h)  55–65 mph (89–105 km/h)  45–55 mph (72–89 km/h)  20–30 mph (32–48 km/h)  
South Dakota^{[47]}^{[48]}  75–80 mph (121–129 km/h)  55–75 mph (89–121 km/h)  65–70 mph (105–113 km/h)  55–65 mph (89–105 km/h)  20–45 mph (32–72 km/h)  
Tennessee  70 mph (113 km/h)  55–70 mph (89–113 km/h)  55–65 mph (89–105 km/h)  35–65 mph (56–105 km/h)  30 mph (48 km/h)  
Texas  75–85 mph (121–137 km/h)  55–75 mph (89–121 km/h)  75 mph (121 km/h)  55–75 mph (89–121 km/h)  25–30 mph (40–48 km/h)  
U.S. Virgin Islands^{[49]}  no freeways in the United States Virgin Islands  55 mph (89 km/h)  30–45 mph (48–72 km/h)  20–25 mph (32–40 km/h)  
Utah^{[50]}^{[51]}  75–80 mph (121–129 km/h)  55–70 mph (89–113 km/h)^{[52]}  55–65 mph (89–105 km/h)^{[53]}  55–65 mph (89–105 km/h)  20–35 mph (32–56 km/h)  
Vermont  65 mph (105 km/h)  55 mph (89 km/h)  55 mph (89 km/h)  50–55 mph (80–89 km/h)  20–50 mph (32–80 km/h)  
Virginia^{[54]}  65–70 mph (105–113 km/h)  55–70 mph (89–113 km/h)  55–60 mph (89–97 km/h)  55 mph (89 km/h)  20–35 mph (32–56 km/h)  
Wake Island^{[1]}  no freeways in Wake Island  40 mph (64 km/h)  
Washington  70 mph (113 km/h)^{[a]}^{[55]}  60 mph (97 km/h)  55–70 mph (89–113 km/h)  65–70 mph (105–113 km/h)  55–65 mph (89–105 km/h)  20–50 mph (32–80 km/h) 
West Virginia  70 mph (113 km/h)  55–65 mph (89–105 km/h)  65 mph (105 km/h)  55 mph (89 km/h)  20–55 mph (32–89 km/h)  
Wisconsin^{[56]}  70 mph (113 km/h)  50–70 mph (80–113 km/h)  65 mph (105 km/h)  55 mph (89 km/h)  20–35 mph (32–56 km/h)  
Wyoming^{[57]}  75–80 mph (121–129 km/h)  60–75 mph (97–121 km/h)  70 mph (113 km/h)  55–70 mph (89–113 km/h)  30 mph (48 km/h) 
legend:  

Freeway: Interstate Highway or other state or federally numbered road built to Interstate standards. Divided: State or federally numbered road, generally with four or more lanes, not built to Interstate standards, but with a median or other divider separating directions of travel. Undivided rural: County, State, or U.S. route, generally with two to four lanes, with no separator between directions of travel. Residential Street/residential: Residential streets, business districts, or School zones. 




State  Typical fine and whether absolute or prima facie* 
Recklessness threshold or enhanced penalty  Ticket dismissal options  Point system 

Arizona  (Not available or information needed.) Prima facie (Absolute above 85 mph (137 km/h)) 
Over 35 mph (56 km/h) in a school zone, over 20 mph (32 km/h) above the posted speed limit, or over 85 mph (137 km/h) regardless of the posted speed limit.^{[58]}  Defensive driving school (requires court approval for criminal speeding tickets).  Point system leading to fines, potential license suspension, increased insurance rates, and potential jail time (if criminal). 
North Carolina  $10–$50 plus court costs.^{[59]} Speeding fines in work zones and school zones are $250 plus court costs. Absolute 
Over 15 mph (24 km/h) over limit at a travelled speed of greater than 55 mph (89 km/h) or over 80 mph (130 km/h)  Prayer for judgment continued (PJC) available depending on the court and subject to their discretion, but not available for charges of exceeding a speed limit by more than 25 mph (40 km/h).  Point system may lead to license suspension. Exceeding the speed limit by more than 15 mph (24 km/h) with a speed of greater than 55 mph (89 km/h) or travelling faster than 80 mph (130 km/h) results in a minimum 30day license suspension.^{[60]} 
Pennsylvania  $35^{[61]} plus court and other costs. All fines doubled in active work zones. Absolute 
Over 30 mph (48 km/h) over limit  None  Point system leads to mandatory driver education and possible license suspension. 
Texas  $1–$200^{[62]} plus court fees. Doubled in active school zones when children are present or construction zones when workers are present.^{[63]} Various additional "fees" assessed by the state essentially increase the fine by around $100 on all tickets. Prima facie^{[64]} 
None^{[65]}  Defensive driving^{[66]} (once per year) or deferred disposition^{[67]} (restrictions vary, but generally at least 4 per year), but only valid if:

Point system is annual surcharge only. No provision for license suspension if surcharges are paid.^{[68]} 
Rhode Island 
(Not available or information needed) Prima facie 
One dismissal every 3 years for speed 14 mph (23 km/h) or less over limit.^{[69]}  
Virginia 
Absolute^{[74]} 
20 mph (32 km/h) over limit or over 80 mph (130 km/h).^{[75]}^{[76]}  Point system^{[77]} leading to fines, suspension, and mandatory driver education.^{[78]} 
Estimated Miles of Highway and Estimated Daily VehicleMiles Traveled by Traffic Volume Group  
Based on arterial and (major) collector sample data from the 2000 Highway Performance Monitoring System^{[79]} 
History
One of the first speed limits in what would become the United States (at the time, still a British colony) was set in Boston in 1701 by the board of selectmen (similar to a city council):
Ordered, That no person whatsoever Shall at any time hereafter ride or drive a gallop or other extream pace within any of the Streets, lanes, or alleys in this Town on penalty of forfeiting three Shillings for every such offence, and it may be lawfull for any of the Inhabitants of this Town to make Stop of such horse or Rider untill the name of the offender be known in order to prosecution^{[80]}
Federal speed controls
In response to the 1973 oil crisis, Congress enacted the National Maximum Speed Law that created the universal 55 miles per hour (89 km/h) speed limit.^{[citation needed]} Whether this reduced gasoline consumption is debated and the impact on safety is unclear; studies and opinions of safety advocates are mixed.
The law was widely disregarded by motorists, even after the national maximum was increased to 65 miles per hour (105 km/h) on certain roads in 1987 and 1988. In 1995, the law was repealed, returning the choice of speed limit to each state.
Upon that repeal, there was effectively no speed limit on Montana's interstates for daytime driving (the nighttime limit was set at 65 mph) from 1995 to 1999, when the state Supreme Court threw out the law as "unconstitutionally vague."^{[81]} The state legislature enacted a 75 mph daytime limit in May 1999.^{[82]}
As of May 15, 2017, 41 states have maximum speed limits of 70 mph or higher. 18 of those states have 75 mph speed limits or higher, while 7 states of that same portion have 80 mph speed limits.
Minimum speed limits
In addition to the legally defined maximum speed, minimum speed limits may be applicable. Occasionally, there are default minimum speed limits for certain types of roads, generally freeways.
Comparable to the common basic speed rule, most jurisdictions also have laws prohibiting speeds so low they are dangerous or impede the normal and reasonable flow of traffic.
Truck speed limits
Some jurisdictions set lower speed limits that are applicable only to large commercial vehicles like heavy trucks and buses. While they are called "truck speed limits", they generally do not apply to light trucks.
A 1987 study said that crash involvement significantly increases when trucks drive much slower than passenger vehicles, suggesting that the difference in speed between passenger vehicles and slower trucks could cause crashes that otherwise may not happen.^{[83]} In a review of available research, the Transportation Research Board said "[no] conclusive evidence could be found to support or reject the use of differential speed limits for passenger cars and heavy trucks" and "a strong case cannot be made on empirical grounds in support of or in opposition to differential speed limits".^{[84]}^{:11}^{:109} Another study said that two thirds (67%) of truck/passenger car crashes are the fault of the passenger vehicle.^{[85]}
Night speed limits
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The basic speed rule requires drivers adjust speeds to the conditions. This is usually relied upon to regulate proper night speed reductions, if required. Numeric night speed limits, which generally begin 30 minutes after sunset and end 30 minutes before sunrise, are occasionally used where, in theory, safety problems require a speed lower than what is selfselected by drivers.
Examples include:^{[citation needed]}
 Some streets in Tucson, Arizona without street lights.
 Some Florida roads near Southwest Florida International Airport near Cape Coral/Fort Myers. (Most of these roads are labeled as "Panther Zones" or "Panther Xing" areas.)
 Daniels Parkway Ext., a fourlane divided highway near SW Florida International Airport with a 50 mph (80 km/h) daytime limit, and a night speed limit of 45 miles per hour (72 km/h) is considered by many to be a speed trap.^{[citation needed]} This road joins neighboring SR 82, a twolane road with a 60 mph (97 km/h) speed limit.
 Colorado Highway 13, with a 65 mph (105 km/h) day/55 mph (89 km/h) night speed limit beginning 7.1 miles north of I70 from north of Rifle to Colorado Highway 64 south of Meeker. Rural Colorado Highway 13 is 55 miles per hour (89 km/h) at night north of Meeker all the way to the Wyoming state line.
 Highway 20 in Washington state between Twisp and Pateros has a 45 mph speed limit due to high numbers of deer (and other wildlife) activity. Deer carcasses can be seen along the road all throughout summer
Some states create arbitrary night speed limits applicable to entire classes of roads. Until September 2011, Texas had a statutory 65 mph (105 km/h) night speed limit for all roads with a higher limit. Montana has a statutory 65 mph (105 km/h) night speed limit on all federal, state, and secondary roads except for Interstates.^{[citation needed]}
Political considerations
Financial concerns
Traffic violations can be a lucrative income source for jurisdictions and insurance companies. For example:
 Westlake, TX took in $42,000 per citizen over nine years for its speed traps.^{[86]}
 Insurance companies may receive several billions of dollars annually in traffic ticket surcharges.^{[87]}
 A study by the Federal Reserve of St. Louis found that traffic ticket writing increases when government revenue decreases.^{[88]}
 2008 debates over traffic enforcement in Dallas County, TX involved concerns of lost profits if ticketwriting decreased.^{[89]}^{[90]}^{[91]}
 In Massachusetts, half of the ticket money goes to the police department that writes the speeding ticket, the other half goes to fund the court that convicts the speeder or collects the fine from them.
Thus, an authority that sets and enforces speed limits, such as a state government, regulates and taxes insurance companies, who also gain revenue from speeding enforcement. Furthermore, such an authority often requires "all" drivers to have policies with those same companies, solidifying the association between the state and auto insurers. 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.^{[92]}
When a speed limit is used to generate revenue but has no safety justification, it is called a speed trap. The town of New Rome, Ohio was such a speed trap, where speeding tickets raised up to $400,000 per year to fund the police department of a 12acre village with 60 residents.^{[93]}
Environmental concerns
Reduced speed limits are sometimes enacted for air quality reasons. The most prominent example includes Texas' environmental speed limits.
Definition of speeding
Either of the following qualifies a crash as speedrelated in accordance with U.S. government rules:^{[94]}
 Exceeding speed limits.
 Driving too fast for conditions.
Speeds in excess of speed limits account for most speedrelated 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 the "exceeding speed limits" definition of speeding is twofold:
 When speed limits are arbitrary, such as when set through political rather than empirical processes, the speed limit's relationship to the maximum safe speed is weakened or intentionally eliminated. Therefore, a crash can be counted as speedrelated even if it occurs at a safe speed, simply because the speed was in excess of a politically determined limit.
 The effective limit may still be too fast for certain conditions, such as limited visibility or reduced road traction^{[95]} or even lowspeed truck rollovers on exit ramps.^{[96]}
Variable speed limits offer some potential to reduce speedrelated crashes. However, due to the high cost of implementation, they exist primarily on freeways. Furthermore, most speedrelated crashes occur on local and collector roads, which generally have far lower speed limits and prevailing speeds than freeways.^{[97]}
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.^{[98]} This allows motorists to defend against a speeding charge if it can be proven that the speed was in fact reasonable and prudent.
Speed limits in Texas,^{[99]} Utah,^{[100]} 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. For example, speed limits in California up to 55 mph, or 65 mph on highways, are prima facie, and those at or above those speeds are absolute.^{[101]}
A successful prima facie defense is rare. Not only does the burden of proof rest upon the accused, a successful defense may involve expenses well in excess of the cost of a ticket, such as an expert witness. Furthermore, because prima facie defenses must be presented in a court, such a defense is difficult for outoftown motorists.
Metric speed limits
Metric speed limits are no longer included in the Federal Highway Administration's Manual on Uniform Traffic Control Devices (MUTCD), which provides guidelines for speed limit signage,^{[102]} and therefore, new installations are not legal in the United States. Prior to 2009, a speed limit could be defined in kilometers per hour (km/h) as well as miles per hour (mph). The 2003 version of the MUTCD stated that "speed limits shown shall be in multiples of 10 km/h or 5 mph."^{[103]} If a speed limit sign indicated km/h, the number was circumscribed and "km/h" was written below. Prior to 2003, metric speed limits were designated using the standard speed limit sign, usually with yellow supplemental "METRIC" and "km/h" plaques above it and below it, respectively.^{[104]}^{[105]}
In 1995, the National Highway System Designation Act prohibited use of federal funds to finance new metric signage.
See also
 Driver License Compact
 NonResident Violator Compact
 Solomon curve
 Traffic violations reciprocity
 Transportation safety in the United States
Notes
 ^ Although the maximum posted speed limit in the state is 70 mph (113 km/h), state law allows a maximum posted speed of 75 mph (121 km/h) (for possible raising of speed limits in the future) on rural freeways.
References
 ^ ^{a} ^{b} Wake Island Code
 ^ ^{a} ^{b} Midway Atoll Code
 ^ "Nixon Approves Limit of 55 MPH". The New York Times. January 3, 1974. pp. 1, 24. Retrieved July 22, 2008. (subscription required)
 ^ ^{a} ^{b} Blair, William G. (4 April 1987). "55m.p.h. Signs Sprout Out West, but New York Region Holds Off". The New York Times. Retrieved 21 August 2016.
 ^ "H.R.2 – 100th Congress (1987–1988): Surface Transportation and Uniform Relocation Assistance Act of 1987". Congress.gov. Library of Congress. 2 April 1987. Retrieved 21 August 2016.
 ^ "Alabama Law Enforcement Agency". Dps.alabama.gov. Retrieved 20170707.
 ^ "Alabama Law Enforcement Agency". Dps.alabama.gov. Retrieved 20170707.
 ^ American Samoa Code Section 22.0323 [1], and Frommer's [2]
 ^ Arizona Statutes Chapter 3 Article 6 State Legislature
 ^ "California Highways with 70 MPH Speed Limits". ca.gov. Retrieved 11 July 2016.
 ^ "Subchapter VIII. Speed Restrictions". Delaware State Legislature. May 19, 2008.
 ^ "Speed limit to jump on Del. 1 near Dover Air Force Base". Retrieved 5 July 2017.
 ^ District of Columbia Municipal Regulations Title 18 – Vehicle and Traffic (March 1997), chapter 22 "Moving Violations" [3] [4]
 ^ "Florida Department of Transportation". state.fl.us. Retrieved 11 July 2016.
 ^ "HB 674 – Maximus Speed Limots; vehicles having greater than 6 wheels". Georgia House of Representatives. May 21, 2008.
 ^ "Guam Code Annotated Title 16 Chapter 3 Article 3 § 3301" (PDF). Justice.gov.gu. Retrieved 20170707.
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^ Nitzman, Alex (20120716). "Nevada @ AARoads – Interstate 80". AARoads.com. Retrieved 20160726.
Contrary to popular belief, the speed limit on Interstate 80 is not 75 mph all the way across Nevada. The speed limit stays at 65 mph from the California line into the RenoSparks metro area and eastward all the way to Milepost 23 near the Mustang Ranch.
 ^ Press, Associated. "Nevada implementing 80 mph speed limit on I80". KSNV. Retrieved 20170506.
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 ^ Utah Code 416a601 – Speed regulations. le.utah.gov.

^ Tribune, The Salt Lake. "70 mph speed limit now official on Utah's urban interstates". sltrib.com. Retrieved 11 July 2016.
The speed limit in Cedar City is 75 mph on I15 besides bypasses that are nearby
 ^ Utah Code 416a602(3)(a)
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 ^ As motorists’ frustration rises, justices of the peace pull out of automated ticket payment program, Dallas Morning News, July 5, 2008
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Law Review
 R. A. Vinluan (2008). "Indefiniteness of automobile speed regulations as affecting validity". American Law Reports—Annotated, 3rd Series. 6. The Lawyers Cooperative Publishing Company; BancroftWhitney; West Group Annotation Company. p. 1326.
 C. C. Marvel (2010). "Meaning of "residence district," "business district," "school area," and the like, in statutes and ordinances regulating speed of motor vehicles". American Law Reports—Annotated, 2nd Series. 50. The Lawyers Cooperative Publishing Company; BancroftWhitney; West Group Annotation Company. p. 343.