Speed limits in the United States

US Speed Limits May 2015

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Speed limits in the United States are set by each state or territory. States have 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.

Overview

The maximum speed limits are set by the state governments and may vary depending on the type of vehicle and the location. For example, in many states, the maximum speed limit for passenger vehicles on rural interstates is 70 mph (113 km/h) to 85 mph (137 km/h), while in urban areas, the maximum limits can be significantly lower. Texas has the highest posted speed limit in the country at 85 mph (137 km/h) on a section of State Highway 130. Conversely, Hawaii posts the lowest maximum speed limit of any state with a maximum speed limit of 60 mph (97 km/h).

History

The history of speed limits in the United States goes back to the early 20th century. In 1901, Connecticut was the first state to pass a speed limit law, with a maximum speed limit of 12 mph (19 km/h) in cities and 15 mph (24 km/h) on country roads. The introduction of the National Maximum Speed Law (NMSL) in 1974, as part of the Emergency Highway Energy Conservation Act, established a national maximum speed limit of 55 mph (89 km/h) to conserve fuel during the oil crisis. In 1987, the US Congress allowed states to increase limits to 65 mph (105 km/h) on certain roads. The NMSL was fully repealed in 1995, returning the power to set speed limits to the states.

Regulation

Speed limits are regulated by both state and local laws. The Department of Transportation (DOT) in each state sets the maximum speed limits on state and federal highways, while local municipalities are responsible for setting speed limits on local roads. Enforcement of speed limits is primarily the responsibility of state and local police forces.

Safety

The impact of speed limits on road safety is a topic of ongoing debate. Proponents of higher speed limits argue that they can lead to smoother traffic flow and reduce the likelihood of accidents due to less variation in vehicle speeds. Critics, however, contend that higher speed limits increase the severity of accidents and the likelihood of fatalities.

Future Trends

There is a growing interest in the use of technology to manage speed limits dynamically. Variable speed limit systems, which adjust speed limits based on traffic, weather conditions, and accidents, are being tested in several states. These systems aim to improve traffic flow and enhance safety on the roads.