The National Maximum Speed Law was a provision in the U.S. federal legislation, Emergency Highway Energy Conservation Act of 1974. The law capped all speed limits at 55 mph (90 km/h). The speed limit was imposed to conserve gasoline in response to the 1973 oil crisis. However, the law was opposed by motorists and most states.
In 1987, the law was amended and the speed limit raised to 65 mph (105 km/h) limits on certain roads. This law was repealed in 1995. And, the authority to set speed limits was given to the states.