Abstract
Statewide crash data bases from nine states were subjected to time series analyses to detect changes in injuries associated with onset of seat belt laws in the respective states. Eighteen comparisons were made of drivers covered by the law, and in all 18 observed casualties were below the number forecast on the basis of prior experience and assuming that no law had been enacted. It is estimated that belts may be reducing 100, 000 additional injuries per year by virtue of the higher usage rates induced.