In 1997 Maryland, Oklahoma, and the District of Columbia upgraded their seat belt laws from secondary to primary enforcement. The objective of this study was to evaluate the change from secondary to primary enforcement in Maryland, Oklahoma, and DC with respect to observed belt use rates, driver reactions, law enforcement practices, citations issued and race. The belt use rate went up in study locations with the implementation of a primary enforcement seat belt law. Four color, 8.5" x 11", 35 pages.