The 1981 Mason-Dixon 500 was a Nextel Cup (then Winston Cup) event held at Dover International Speedway on May 17, 1981. Neil Bonnett dominated the afternoon, leading 404 miles, just over 80% of the race. On lap 459, Bonnett was holding a two-lap lead over second-place Cale Yarborough when his day ended with engine failure, giving the lead to Yarborough. Yarborough was five laps ahead of Jody Ridley when he retired from the race with engine trouble with 20 laps remaining, and Ridley went on to win won his only career event as well as the only win in the fifty-year history of Donlavey Racing. Bobby Allison finished second and held a 168-point championship lead on Ricky Rudd, who came home fifth.