Fewer deaths than initially projected for the second half of 2003, helped by more seat belt use, pushed overall U.S. highway fatalities down for the year to 42,643.

The National Highway Traffic Safety Administration revised down the 13-year high of 43,220 deaths it reported earlier, based on actual figures.

Deaths involving drunk driving and vehicle rollover declined, regulators said, and NHTSA Administrator Jeffrey Runge attributed the drop in fatalities to a 4 percent increase in seat belt use nationwide.

The fatality rate per 100 million vehicle miles traveled was 1.48 in 2003, down from 1.51 in 2002.

While the actual number of rollover deaths declined 3.3 percent in 2003, rollover fatalities associated with sport utility vehicles rose 6.8 percent.

Rollovers represent only a small fraction of crashes on U.S. roads but more than a quarter of all traffic deaths. Most rollover deaths occur in single-vehicle accidents.