IMSA SportsCar Championship

On September 5, 2012, it was announced that the Grand-Am Road Racing sanctioning body would merge with the Braselton-based International Motor Sports Association, and as such, both bodies would merge their premiere sports car series, the Rolex Sports Car Series and American Le Mans Series respectively, with plans to debut in 2014. On November 20, 2012, the merger committee announced that SME Branding were selected to develop the name, logo and identity of the new series.

On January 8, 2013, the two series' announced a preliminary class structure for the new merged series. Grand-Am's Daytona Prototype category and IMSA's P2 would combine into a single-prototype class, with allowances for the unique DeltaWing to also compete in the new class. The Le Mans Prototype Challenge class of single spec cars from the American Le Mans Series would continue as is, although the cars were to switch to Grand-Am's Continental Tires. The GT class of the American Le Mans Series would remain unchanged, while Grand-Am's GT class would form another GT class, and be combined with the American Le Mans GTC category. The only category of cars not represented in the new series is the American Le Mans Series' P1 category.

The reveal date for the new series was March 14, 2013 at the Chateau Élan Hotel and Conference Center at Sebring International Raceway, two days before the 12 Hours of Sebring. American Le Mans CEO Scott Atherton announced the new sanctioning body would remain IMSA while Ed Bennett revealed the new titles for the series' five classes. SME Branding Senior Partner Ed O'Hara then announced the new United SportsCar Racing title and logo, a name submitted through a contest won by Louis Satterlee of Florida, a racer in the Florida Karting Championship Series.

On August 9, 2013, Fox Sports 1 announced it had signed a TV contract with IMSA to televise the entire USCC season between 2014 and 2018.

On September 12, 2013, Tudor was announced as the title sponsor for the series, which was named the United SportsCar Championship. On August 8, 2015, WeatherTech was announced as the new title sponsor for the series, renaming the series to the WeatherTech SportsCar Championship, starting with the 2016 season.

Beginning with the 2019 season, the series is covered exclusively by NBC Sports in the United States. The NBC broadcast network will air nine hours of coverage annually, with the majority of the coverage airing on NBCSN. CNBC and the NBC Sports app will provide supplemental coverage. Beginning with 2022, USA Network replaced NBCSN as the cable home to the series.

Originally based on a Canadian series before being acquired by Grand-Am, the Continental Tire Sports Car Challenge (originally known as Grand-Am Cup) is a production-based touring car series. The series is split into two classes known as Grand Sport (GS), intended for large capacity GT-style cars, and Street Tuner (ST), consisting of smaller sedans and coupes, some of which are front-wheel drive. The IMSA Continental Tire Sports Car Challenge until 2013 supported some Rolex Series races but also headlined some of its own dates. This series continued with the United SportsCar Championship after the merger and is somewhat comparable to the old Trans Am Series.

The IMSA Michelin Endurance Cup (MEC) is a championship for drivers, teams and manufacturers, which comprises the five endurance races on the IMSA WeatherTech SportsCar Championship schedule. It began in 2014 in the inaugural United SportsCar Championship season, where it was called the Tequila Patrón North American Endurance Cup. In 2019, Michelin became the title sponsor. The current five races that award MEC points are the 24 Hours of Daytona, 12 Hours of Sebring, 6 Hours of Watkins Glen, SportsCar Endurance Grand Prix and the Petit Le Mans.

Points are awarded at varying intervals depending on the length of the race. Six hour races award points at three hours and the finish, while Petit Le Mans offers points at four, eight and ten hours. Sebring awards points every four hours and Daytona awards them every six hours.

There are four classes in the IMSA SportsCar Championship series, featuring two sports prototype categories and two grand tourer classes. Some races may only use selected classes of cars; for example, any class car may be permitted entry at Daytona, the Chevrolet Grand Prix at Mosport does not feature the Grand Touring Prototype (GTP) class, while at the appropriately-named GT Challenge at VIR only GT Daytona Pro (GTD Pro) and GT Daytona (GTD) cars are entered. Grand Touring Prototype (GTP), Le Mans Prototype 2 (LMP2), and Grand Touring Daytona (GTD) cars are compatible with regulations for the 24 Hours of Le Mans.

Classes are also distinguished by regulations on driver lineups, using a rating system. GTP and GTD Pro have no restrictions; however, teams competing in LMP2 can only field one gold driver, and teams competing in GTD must field one "amateur" driver with a bronze or silver rating.

Sports Prototype classes

Grand Touring Prototype (GTP)

The flagship class of the championship that replaced the DPi (Daytona Prototype International) class starting in 2023, featuring cars built to IMSA's LMDh and Automobile Club de l'Ouest's Le Mans Hypercar regulations.

Le Mans Prototype 2 (LMP2)

A class introduced since 2019 after being split from the DPi class (2019–2022), it features pro-am driver lineups. The class features cars built by Automobile Club de l'Ouest's (ACO) 4 licensed manufacturers (Riley-Multimatic, Ligier, Oreca and Dallara) to the specifications of the FIA/ACO 2017 Global LMP2 regulations.

Grand Touring classes

GT Daytona Pro (GTD Pro)

A class that utilizes the FIA GT3 specifications that replaced the GTLM class starting in the 2022 Season. GTD Pro is an "open" class with no driver rating restrictions.

GT Daytona (GTD)

A class active since 2016 that uses the same specification cars as GTD Pro, but with stricter driver requirements; at least one Silver or Bronze driver must be in a team and teams are limited to only one platinum driver per car.

There were five classes formerly used in the IMSA SportsCar Championship series, featuring four sports prototype categories and one grand tourer class.

Sports Prototype classes

Daytona Prototype International (DPi)

The former flagship class of the championship from 2019 to 2022, featuring cars built to IMSA's Daytona Prototype International regulations, which are based upon the 2017 Le Mans Prototype LMP2 cars. Previously, the DPi's had competed against their base LMP2 counterparts in the Prototype class from 2017 to 2018. Starting in 2019 the LMP2 cars were split into a separate class. The Prototype class had originally consisted of Grand-Am's Daytona Prototypes with the American Le Mans Series LMP2 prototypes, and the DeltaWing, before the original Daytona Prototypes, and the DeltaWing were phased out of competition at the end of 2016, and replaced by the new DPi cars. Starting in 2023, the DPi class was replaced by the GTP class in an effort to further improve the racing in the Prototype class, as well as create a closer bond to the FIA World Endurance Championship.

Prototype (P)

The former flagship class of the championship from 2014 to 2018 before splitting into two separate classes in 2019, featuring cars built to which included classes of prototypes carried over from the previous motorsport category series of the American Le Mans Series and the Grand-Am Rolex Sports Car Series. These cars were Daytona Prototypes, LMP2 prototypes & the Nissan DeltaWing. Starting in 2017 the original Daytona Prototypes, and the DeltaWing were phased out of competition, and replaced by the new DPi cars. At the end of the 2018 WeatherTech SportsCar Championship season this class would be split into two separate classes, DPi & LMP2 for the following season in 2019.

Prototype Challenge (PC)

This was a one-make spec class in which all cars that drivers and teams used were Oreca FLM09 LMPC's powered by 6.2L Chevrolet V8 engines which made 430 hp each. This class would be used from the 2014 season until the end of the 2017 season.

Le Mans Prototype 3 (LMP3)

Introduced in the 2021 season, having been in the IMSA Prototype Challenge category as one of the feeder series to the IMSA WeatherTech SportsCar Championship, this class of prototypes features cars built according to ACO's 2020 LMP3 Generation II ruleset specifications from manufacturers such as Ligier, ADESS, Ginetta & Duqueine Engineering. The class was removed after the 2023 season due to the growth in grid sizes. LMP3s now race as part of the IMSA VP Racing SportsCar Challenge, a support series for the main IMSA championship.

Grand Touring classes

GT Le Mans (GTLM)

A continuation of the ALMS GT class, it consisted of cars matching the ACO's GTE specification and competed in the series between the 2014 and 2021 seasons.

Drivers

Teams

Manufacturers