A brief campaign in May to enforce seat-belt laws in eight Southern states, supplemented by television and radio advertisements, pushed use up by nine percentage points, government figures show. Now safety advocates say they will press the government to adopt the strategy nationwide. The campaign, conducted in the days leading up to Memorial Day, raised seat-belt use to about 74 percent, slightly higher than the national average, according to the National Highway Traffic Safety Administration (NHTSA). Officials attribute the rise in seat-belt usage to 118,000 tickets being issued for failing to wear belts or failing to put children into appropriate restraints, and a $3.75 million advertising campaign, mostly on television, to warn drivers about increased enforcement.