The Watkins Glen Grand Prix was first held in 1948 on a 6.6-mile course that wound through Watkins Glen State Park and the streets of the village. Cameron Argetsinger, a Cornell law student and SCCA member, organized the event with the local Chamber of Commerce. The inaugural eight-lap race was won by Frank Griswold in a pre-war Alfa Romeo 8C.
The early street course proved dangerous. In 1950, three spectators were injured during a support race, and driver Sam Collier was killed during the Grand Prix. In 1952, twelve spectators were injured and one killed when a car left the circuit in the village. These tragedies prompted organizers to relocate the race to a hillside course outside Watkins Glen in 1953. Persistent complaints about visibility and run-off areas led to the construction of a permanent circuit, today known as Watkins Glen International, which opened in 1956.
The event was expanded to six hours in 1968 and joined the World Sportscar Championship. Alongside the 24 Hours of Daytona and the 12 Hours of Sebring, the Six Hours of Watkins Glen served as an American round of the WSC from 1968 until 1981, traditionally contested during the summer months. The circuit's bankruptcy and the FIA's decision not to return World Championship racing to the United States in 1982 caused the event to lapse.
The race returned in 1984 under IMSA as part of the Camel GT Championship, though in a radically altered format. The 1984 edition was split into two separate three-hour heats, styled the Camel Continental, with a break between segments. The format changed again in 1985, separating sports prototypes and grand touring cars into distinct three-hour events before being consolidated into a single 500-mile race in 1986, then shortened to 500 km in 1987.
Through the late 1980s and 1990s, IMSA maintained both a Continental (prototype) race and the New York 500 (grand touring). The New York 500 was dropped in 1992. By 1996, IMSA restored the Watkins Glen event to its historic combined prototype-and-grand-tourer format. A period of instability followed as the USRRC collapsed during 1999; the Grand American Road Racing Championship then operated the race as part of the Rolex Sports Car Series from 2000 until the 2014 merger.
Following the 2014 unification of Grand-Am and the American Le Mans Series under IMSA, the event returned to its traditional six-hour format and became a central fixture of the IMSA WeatherTech SportsCar Championship. It is one of five races that count toward the IMSA Michelin Endurance Cup, the championship's endurance sub-series, with points awarded at the three-hour mark and at the finish. Watkins Glen International's flowing, undulating layout — a 5.43 km permanent road course — is particularly well suited to sports car racing and the event draws strong manufacturer support.
The COVID-19 pandemic disrupted the 2020 race: New York state authorities would not permit NASCAR Holdings to host events at Watkins Glen, and the race was relocated to Road Atlanta.
The Six Hours of Watkins Glen is one of the tent-pole events of North American sports car racing, sitting alongside the Rolex 24 at Daytona and the 12 Hours of Sebring as a marquee date on the IMSA calendar. Its nearly eight decades of history, interrupted only by periods of sanctioning instability and the pandemic, make it one of the most enduring events in American motorsport.