IMSA

History

John Bishop, a Sikorsky employee, entered motorsport in the 1950s after meeting Dave Allen, a Sports Car Club of America (SCCA) staff member, who offered him a management position on the SCCA Contest Board. Bishop moved to Westport, Connecticut, and his duties included defining technical rules, general administration of SCCA competition, and providing artwork for the club's magazines and event programmes. He developed a good relationship with SCCA president James H. Kimberly.

In 1958, the SCCA created a new executive director position, filled by Hugo Rush, who later contributed to Allen's departure. Despite a poor relationship with Rush, Bishop gained experience and demonstrated managerial qualities. By 1962, the SCCA managed major World Championship for Makes rounds at Daytona, Sebring, Bridgehampton, and Watkins Glen, and was involved in the United States Grand Prix. Bishop helped create the USRRC series for Group 7 sports cars to recover races taken by USAC, and was instrumental in founding the SCCA Trans-Am series and the SCCA/CASC Can-Am series.

Tension and in-fighting led Bishop to resign in 1969. Bill France Sr., who founded NASCAR and wanted to promote road racing, financed IMSA's creation after discussions with Bishop. Bishop was given sole control of the organization, with France owning 75% of the stock and Bishop 25%. The articles of incorporation were filed in Connecticut on June 23, 1969.

Current sanctioned series

The IMSA SportsCar Championship began in 2014 after Grand-Am Road Racing and the American Le Mans Series combined. It first raced as the Tudor United SportsCar Championship at Daytona International Speedway in late January 2014. WeatherTech took over as title sponsor in 2016. The series now includes LMDh, LMP2, and GT3 cars.

The IMSA Michelin Pilot Challenge is a grand touring and touring car series that started as the support series for GRAND-AM’s Rolex Sports Car Series. When the merger happened in 2014, it became the support series for the new United SportsCar Championship. Continental Tire was the title sponsor from 2010 through 2018, and Michelin took over both supply and sponsorship in 2019. This series uses TCR Touring Cars and GT4 cars.

The IMSA VP Racing SportsCar Challenge is a development series that replaced the IMSA Prototype Challenge in 2023. It features LMP3 and GT4 cars and usually runs alongside WeatherTech Championship events. Most races are two 45-minute sprints with no pit stops or driver swaps. Starting in 2026, the Airbnb Endurance Challenge was added, where LMP3s and a one-make BMW M2 class race for two hours with two drivers per team and a mandatory driver change.

This endurance event awards points to both the main championship and a separate endurance points table with its own trophy and prizes. Unlike the old Prototype Challenge, this series runs multi-class racing with prototypes and GTs on track together. For sprint weekends, drivers must hold Silver or Bronze FIA ratings. For Endurance Challenge weekends, each team needs one Silver or Bronze driver, while the other driver can be Gold-rated.

Defunct series

The International Sedan Series was short-lived and served as the genesis of the Radial Sedan Series. It is unclear whether the 1969 inaugural IMSA Sedan race at the Talladega Superspeedway Road Course was designated International Sedan Series, as that was the only race held that year. Over the winter of 1969–70, rules were officially promulgated for the series, initially to be known as the International 100 Series for sedans up to 100 c.i. or 1600 cc., but revised before the 1970 season to include larger engines, presumably prompting the name change to International Sedan Series.

In 1971, the series was revamped and became the Radial Sedan Series, requiring DOT radial tires. New rules divided cars over 1.6 L into two classes: Class A for sedans under 2 L (overhead cam engines limited to 1.6 L), and Class B for larger engines up to the AMC Gremlin's 232 c.i. The "Baby Grand" moniker was a nickname for these IMSA series, distinct from the NASCAR-sanctioned Baby Grand series (later Goody's Dash Series). Some RS regulars, such as Carson Baird driving a Dodge Colt, competed in both series with minimal rule adjustments.

The IMSA RS Series began in 1971, originally sponsored by B.F. Goodrich as the Goodrich Radial Challenge, until sponsorship dropped midway through 1975 or 1976, then by Goodyear as the Goodyear Radial Challenge, and later as the Champion Spark Plug Challenge.