The nation's two leading sports-car racing series, Grand-Am Road Racing and the American Le Mans Series, said Wednesday they plan to merge in 2014.
"This merger will strengthen professional sports-car racing beyond what either of our organizations could have achieved separately," ALMS founder Don Panoz said in a statement.
Both series hold races -- some of them long endurance events -- that feature different classes of sports cars, led by the exotic Daytona prototype cars in Grand-Am and the LMP1 cars in the ALMS.
Grand-Am's schedule includes the Rolex 24 at Daytona, a 24-hour endurance race at Daytona International Speedway.
Some of their races are included in weekend events that include several forms of racing. ALMS, for instance, holds one of its races during the weekend of the Toyota Grand Prix of Long Beach, an IndyCar race, on the streets of Long Beach.