The National Maximum Speed Limit (NMSL) was a provision of the federal government of the United States 1974 Emergency Highway Energy Conservation Act that effectively prohibited speed limits higher than 55 miles per hour (89 km/h). It was drafted in response to oil price spikes and supply disruptions during the 1973 oil crisis and remained the law until 1995. While federal officials hoped gasoline consumption would fall by 2.2%, the actual savings were estimated at between 0.5% and 1%. The law's safety benefit is disputed as research found conflicting results.