The 55 mph speed limit was a federally mandated speed limit in the United States during the 1970s and early 1980s. It was imposed as a measure to conserve fuel and increase highway safety during the oil crisis of the 1970s.
The oil crisis of 1973, triggered by the Arab oil embargo, led to a sharp increase in fuel prices and shortages in the United States. To reduce fuel consumption and dependence on foreign oil, the U.S. government implemented various energy conservation measures. One such measure was the imposition of a national speed limit of 55 mph (88.5 km/h) on all highways and interstates through the Emergency Highway Energy Conservation Act in 1974.
By reducing the speed limit, the government aimed to achieve several objectives:
Fuel conservation: Lowering the speed limit was believed to decrease fuel consumption since vehicles are generally more fuel-efficient at lower speeds. Reducing speed limits was seen as a way to stretch the available fuel supply during the energy crisis.
Improved safety: There were claims that lower speed limits would reduce the severity of accidents and save lives. The rationale was that lower speeds would result in less force during collisions, potentially reducing the number of serious injuries and fatalities.
Encourage public transportation: By making car travel less convenient and slower, the hope was that people would consider alternative transportation methods, such as public transit, carpooling, or bicycling, further reducing the demand for gasoline.
The 55 mph speed limit remained in place until the late 1980s when, in 1987, the federal government allowed states to raise their speed limits on rural interstates to 65 mph. Then, in 1995, the federal government completely repealed the national maximum speed limit, giving states the authority to set their own speed limits.
Today, speed limits vary widely across the United States, with many states setting their speed limits at 70 mph or higher on certain highways and interstates. Speed limits are typically determined based on factors such as road conditions, traffic patterns, engineering assessments, and safety considerations.