From the late 1990s through 2013, top-level sports car racing in North America was split between two rival organisations with contrasting philosophies. The American Le Mans Series, sanctioned by IMSA, catered to high-technology prototype and GT machinery closely aligned with the regulations of the 24 Hours of Le Mans. The Rolex Sports Car Series, run by Grand American Road Racing, emphasised cost control and accessibility, most visibly through the purpose-built Daytona Prototypes introduced in 2003.
On 5 September 2012 Grand-Am announced that both organisations would merge and their respective premier series would be combined into a single unified championship beginning in 2014. The new sanctioning body retained the IMSA name while the series title was chosen by public contest, with the name United SportsCar Racing submitted by a Florida kart racer named Louis Satterlee. Tudor was announced as the series' first title sponsor in September 2013, and the championship launched as the Tudor United SportsCar Championship.
The merged series launched in 2014 with five classes designed to accommodate the most competitive categories carried over from both predecessors. The Prototype (P) class combined Grand-Am's Daytona Prototypes with IMSA's LMP2 cars and the Nissan DeltaWing, forming a single flagship prototype category. The Prototype Challenge (PC) class was a spec category using Oreca FLM09 cars powered by 6.2-litre Chevrolet V8 engines producing 430 horsepower. GT Le Mans (GTLM) continued the American Le Mans Series' GTE-specification GT machinery with manufacturers including Corvette, Porsche, Ferrari, and BMW. GT Daytona (GTD) used FIA GT3-specification cars and mandated at least one amateur co-driver. A brief GX alternative-fuel class was also incorporated from the Rolex Series' final season.
The series built its calendar around a combination of short-distance sprint races and long-distance endurance rounds. The Rolex 24 at Daytona opened each season and the Petit Le Mans at Road Atlanta served as the season finale. The championship introduced the Tequila Patrón North American Endurance Cup, later renamed the Michelin Endurance Cup, which tracked performance across the series' five longest races including the Rolex 24, 12 Hours of Sebring, and 6 Hours of Watkins Glen.
Fox Sports 1 held the broadcast rights to the series during its Tudor-branded years after signing an agreement with IMSA in August 2013 covering the 2014 through 2018 seasons.
In August 2015, WeatherTech — a manufacturer of automotive accessories — was announced as the new title sponsor, and the series was renamed the IMSA WeatherTech SportsCar Championship beginning with the 2016 season. The Tudor brand's two-year association bookended the critical launch period of the unified series, providing commercial stability as the merged championship established itself as the definitive home of sports car racing in North America. The underlying format, class structure, and calendar philosophy introduced under the Tudor banner remained the foundation the WeatherTech championship built upon.