Speed Limit Fact Sheet ( PDF )
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AAA Foundation for Traffic Safety
Press Release
1730 M. Street, N.W., Suite 401
Washington, D.C. 20036
Fax: (202) 775-1459 Phone: (202) 775-1456

In 1987, many states raised the maximum speed limtis from 55 to 65 mph on portions of their rural interstate highways. There was intense debate about the consequences of this change. Proponents of differing views on the impact of the higher speed limits quickly rushed with early data to support their positions.

Latest national figures show a continuing gradual decline in mileage death rates and in actual numbers of highway deaths. Rural freeway deaths – locations most impacted by the higher 65 speed limit were 2,870 in 1988; 2,775 in 1989, and 2,728 in 1990. Despite these figures, critics of the higher speed limit continue to resist the change.

Charles Lave, Chairman of the Department of Economics of the University of California, Irvine suggests in his study, “Did the 65 MPH Speed Limit Save Lives?” that states which had adopted the higher speed limit actually showed greater improvement in their overall statewide fatality rates than those states which maintained the lower maximum speed limit. Dr. Lave is no stranger to this issue. He was amember of the Transportation Research Board Committee for the Study of the Benefits and Costs of the 55 MOH National Maximum Speed Limit.

In 1984, this Committee produced the Special Report 204, “55: A Decade of Experience” which gave qualified support in favor of maintaining the lower maximum speed limit on all roads because of projected estimates of lives saved through the national speed mandate.

Why did the higher speed limit on rural interstate highways result in lower fatality rates? Dr. Lave’s study suggests the following events may have taken place:

  1. Drivers may have switched to use the higher speed roads which are safer and better designed
  2. highway patrols may have shifted resources to activities with more safety pay-off, and
  3. the speed variance among cars declined – it might decline on the interstates as law-abiding drivers caught up with the speeders, and it might have declined on other highways as their speeders switched to the interstates.

Dr. Lave reports that his evidence indicates that events (1) and (2) actually did occur but no evidence is available to support or deny the occurrence of the reduction of the speed variance.

Dr. Lave’s report was supported by grants from the AAA Foundation for Traffice Safety and the University of California Transportation Center.

Copies may be obtained from:

AAA Foundation for Traffic Safety
1730 M Street, N.W., Suite 401
Washington, D.C. 20036.

You can download the study here.