Speed limits in the United States

[3][4] Unusual for any state east of the Mississippi River, much of Interstate 95 (I-95) in Maine north of Bangor allows up to 75 mph (121 km/h), and the same is true for up to 600 mi (966 km) of freeways in Michigan.

Portions of the Idaho, Montana, Nevada, Oklahoma, 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 Texas State Highway 130, a toll road that bypasses the Austin metropolitan area for long-distance traffic.

This table contains the most usual posted daytime speed limits, in miles per hour, on typical roads in each category.

Undivided rural: County, State, or U.S. route, generally with two to four lanes, with no separator between directions of travel.

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[86]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.

As stated, in part: ...the Secretary of Transportation shall not approve any project under section 106 of title 23 of the United States Code in any State which has...a maximum speed limit on any public highway within its jurisdiction in excess of 55 miles per hour...[88]In 1984, a comprehensive study by the National Research Council found that the lower speed limits contributed to saving 3,000 to 5,000 lives in 1974 and from 2,000 to 4,000 lives each year thereafter, due to slower and more uniform speeds on American highways.

In 1995, the law was repealed by the National Highway System Designation Act of 1995, returning the choice of speed limit to each state.

[90] Upon that repeal, there was effectively no speed limit on Montana's highways for daytime driving (the nighttime limit was set at 65 miles per hour (105 km/h)) from 1995 until 1999, when the state Supreme Court threw out the law requiring a "reasonable and prudent" speed as "unconstitutionally vague.

Hawaii has the lowest maximum speed limit, with its freeways and Saddle Road being signed at up to 60 miles per hour (97 km/h).

"[95] Some jurisdictions set lower speed limits that are applicable only to large commercial vehicles like heavy trucks and buses.

[96] 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".

Furthermore, such an authority often requires "all" drivers to have policies with those same companies, solidifying the association between the state and auto insurers.

Speed limits in various states, including Texas,[114] Utah,[115] Massachusetts, New Hampshire, Connecticut, Ohio, Oregon, and Rhode Island are prima facie.

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.

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,[117] and therefore, new installations are not legal in the United States.

[119] In 1995, the National Highway System Designation Act prohibited use of federal funds to finance new metric signage.