IMSA

IMSA, the International Motor Sports Association, is the primary sanctioning body for sports car racing in North America. Founded in 1969, IMSA has overseen a range of sports car series over the decades and today runs the IMSA WeatherTech SportsCar Championship, the top level of sports car endurance racing in the United States and Canada.

The WeatherTech Championship typically features multiple classes racing together on the same track at the same time, including top-tier prototype cars and production-based GT cars, a format that allows different types of machinery and driver lineups to compete for class wins within a single event. This multi-class structure is common in endurance racing and allows manufacturers and teams with different budgets and technical approaches to compete on shared bills.

IMSA's calendar includes long-standing endurance classics such as the Rolex 24 at Daytona and the Sebring 12 Hours, events that test both car durability and team strategy over many hours of continuous racing. IMSA has also coordinated technical convergence with the FIA World Endurance Championship in its top prototype class, allowing some cars to compete in both series' events, including at Le Mans.