Safety-belt-use laws in only 21 states and the District of Columbia are primary, meaning police may stop vehicles solely for belt law violations.
In most states belt-use law enforcement is secondary, so police cannot stop vehicles for this infraction alone. New Hampshire is the only state without a belt-use law.
"In states with primary laws, safety-belt-use rates are higher. The result is that crash deaths are reduced," says Institute senior vice president Susan Ferguson.
Belt-use rates averaged 84 percent in primary states compared with 73 percent in secondary states, according to the most recent national observational survey conducted in 2004 by the National Highway Traffic Safety Administration.