The last United States Grand Prix held in Phoenix was on March 10, 1991, with Senna again claiming victory in a modified layout reducing the length to 2.31 miles. Again reliability was a factor, with only nine cars still running at the end of the race. For a second straight season both Tyrrells finished in the points; Stefano Modena, who had replaced the Ferrari-bound Alesi, in fourth heading Nakajima in fifth.