All the team traveled to Watkins Glen from Canada, while some of the drivers went to Michigan for a CanAm race on the intervening weekend. Others flew back to Europe for the Paris 1000 sportscar race which was won by Matra's Jean-Pierre Beltoise with Pedro Rodríguez second in a similar car. Matra's third driver Johnny Servoz-Gavin flew to Rome, won an F2 race and then flew back to the US.

The field reassembled at Watkins Glen with the field largely unchanged. Mario Andretti was back in the four-wheel-drive Lotus 63 while Bill Brack had been replaced in the third BRM by George Eaton. There was still only one Ferrari, entered by NART for Pedro Rodríguez.

Rindt was fastest in qualifying in his Lotus, beating Denny Hulme's McLaren by 0.03s while World Champion Jackie Stewart was third on the 2 x 2 grid alongside Graham Hill's Lotus. Jo Siffert was fifth with sixth place on the grid going to Bruce McLaren, although the New Zealander failed to make the start because of mechanical problems during the reconnaissance laps before the race. Rindt took the lead at the start with Stewart and Hill in pursuit while Hulme dropped back to ninth during the first lap and pitted soon afterwards.

On the third lap Siffert managed to pass Hill and he was soon overtaken by Beltoise and Piers Courage in the Frank Williams Brabham. Siffert retired soon afterwards and as Courage had passed Beltoise (who was in trouble with gears), it was the Englishman who was running third.

On lap 12 Stewart overtook Rindt to go into the lead. Nine laps later Rindt was in the lead again. Rindt was able to pull away this time and Stewart's Matra began to trail smoke and he retired with engine failure on lap 36. This left Courage in second, 40 seconds behind Rindt, although he was battling for the position with Brabham and Ickx. Eventually both the factory Brabhams hit trouble, Ickx retiring with engine failure and Brabham being forced to pit for more fuel and so Surtees moved into third place in his BRM.

Hill was running in sixth place in the mid-race. He had a spin and had to push-start his car. As a result he was unable to do up with seat belts and on lap 91 he spun again. This time the car overturned and Hill was thrown out, breaking both his legs.