According to a recent study by the Insurance Institute for Highway Safety (IIHS), higher speed limits have caused 33,000 deaths nationwide since 1995. The study found that each 5 mph increase in the maximum speed limit resulted in a 4% increase in fatalities. States began increasing their maximum speed limits after the Emergency Highway Energy Conservation Act was repealed in 1995.
The act was signed by President Nixon in 1974 in response to the Organization for Petroleum Exporting Countries' embargo against the United States, which caused oil prices to quadruple. The law set all national highway speed limits at 55 mph (they previously ranged from 40 mph to 80 mph) and penalized states that did not comply with the new speed limit by withholding federal funds. The law was intended to force Americans to drive at a more fuel-efficient speed, but it also decreased the number of automobile-related fatalities.
The IIHS study found that travel speeds increased after the act was repealed. Researchers found that fatalities increased on rural interstates when the law was partially repealed in 1987, then on all interstates after it was repealed in its entirety. Today, every state has a maximum speed limit over 55 mph. Six states have 80 mph limits, and drivers in Texas can drive 85 mph on certain roads.