The IMSA SportsCar Championship, currently known as the IMSA WeatherTech SportsCar Championship under sponsorship, is a sports car racing series based in the United States and Canada and organized by the International Motor Sports Association (IMSA). It is a result of a merger between two existing North American sports car racing series, the American Le Mans Series and Rolex Sports Car Series. At its inception, the name was United SportsCar Championship, which subsequently changed to IMSA SportsCar Championship in 2016. Rolex SA's Tudor brand was the championship's title sponsor in 2014 and 2015, and since 2016 WeatherTech has served as title sponsor.

Sports car racing is a form of motorsport road racing which utilises sports cars that have two seats and enclosed wheels. They may be purpose-built prototypes or grand tourers based on road-going models. Sports car racing is one of the main types of circuit auto racing, alongside open-wheel racing, touring car racing and stock car racing. Sports car races are often, though not always, endurance races that are run over particularly long distances or large amounts of time, resulting in a larger emphasis on the reliability and efficiency of the car and its drivers as opposed to outright car performance or driver skills. The FIA World Endurance Championship is an example of one of the best known sports car racing series.