The 1971 United States Grand Prix, after the cancellation of the Mexican Grand Prix, was the final race of the season. With the large prize fund, the race attracted a very strong entry. Since the 1970 race, the circuit had undergone a major rebuilding. The track had been resurfaced and widened to a uniform 36 feet (11m) all around, and guard rail now lined the entire track. The pits (along with the start/finish line) had been moved, and more than doubled in size, with a four hundred foot long garage immediately behind. There was a new press building, new grandstands and a new section of track to the southwest, adding almost a mile to the length. Many were now describing the track as the finest road circuit in North America.
In the race itself, Tyrrell driver François Cevert scored his first (and, tragically, his only) Formula One victory.
Brabham: For this race only, Chris Craft's car was entered with the factory team. Otherwise there were no changes.
BRM: The team had five entries again. Canadian John Cannon was supposed to rent a March to drive, but when the car was unavailable, he cut a deal for BRM's P153, and Helmut Marko got one of the P160s. All of the P160s except for Howden Ganley's car had Mark II cylinder heads.
Ferrari: The team had brought one of the 1970 312Bs as a spare, and Jacky Ickx used it in the race. Mario Andretti had a problem in that the USAC race at Trenton, NJ had been rained out the previous week, and was now scheduled to be held on the same day as the Grand Prix.
McLaren: Nothing changed since Mosport, including the questions about the team's future.
The Roger Penske-entered car also had an issue, as Mark Donohue was supposed to drive in the same USAC race as Andretti. In case Donohue would be unable to drive at Watkins Glen, David Hobbs was selected as an alternate.
Surtees: Rolf Stommelen's frustrating season with Surtees ended a race early, when he contracted a tooth infection, and would not be able to drive. Mike Hailwood was already signed to drive the third car, so John Surtees had a competition during practice between Gijs van Lennep and Sam Posey for Stommelen's car. It was not until after practice that Surtees decided to let Posey drive. Surtees himself was driving the full-width nose and side radiator car that first appeared at Monza, and would be called a TS9B next season.
Tyrrell: For this race the team entered the original 001 chassis with new Can-Am Champion Peter Revson.