Speed can be a major cause of serious and even fatal traffic accidents. The federal government’s 24-year-old decision allowing states to raise speed limits over 65 miles per hour caused almost 14,000 additional fatalities in motor vehicle accidents, according to a recent Insurance Institute for Highway Safety study.

This was an average of 560 deaths each year. It is just 10 percent of the deaths, however, anticipated by federal officials and safety advocates in 1995 when the 65 mile per hour national speed limit was repealed by Congress. The study found that a five mile per hour increase in the speed limit raised the number of interstate fatalities by approximately 8 percent. A 10 mile per hour increase raised the number of traffic deaths by 17 percent. Fatalities, however, grow exponentially and a 15 mile per hour rise increases fatalities by 27 percent.

The study focused on interstate and freeways because these roads have high speeds and precise data exists on the location and when speed limits changed. However, motorists may drive faster on secondary roads after being used to the higher speeds on the interstates. Higher speed limits were also raised on these secondary roads. There was an increase of 23,000 fatalities on these roads.

Speeding was a major factor in approximately one-third of all traffic fatalities, according to the National Highway Traffic Safety Administration. However, overall accident fatalities fell from approximately 40,000 from 1993 to 37,000 in 2017. This decline is attributed to the attention devoted to impaired and distracted driving. Vehicles are now equipped with better crash protection for occupants and crash avoidance technologies, such as electronic devices that correct skids, collision warnings and automatic braking. Increased speed does not save much time. The study’s author said that driving 100 miles at 65 miles per hour is only seven minutes longer than going at 70 miles per hour.