The 1975 Mason-Dixon 500 was a 500-lap NASCAR Winston Cup Series race held at Dover Downs International Speedway in Delaware. Originally scheduled for Sunday, May 18, the event was heavily affected by thick fog and mist, forcing officials to stop the race after just 17 laps. It was restarted and completed on Monday morning, with a total attendance of 32,000 on Sunday and 15,000 on Monday.
A field of 35 cars started the race, with David Pearson winning the pole position at a speed of 136.612 mph in the #21 Wood Brothers Mercury. The race was slowed significantly by eight cautions for 101 laps, resulting in a slow average speed of just 100.820 mph. Pearson dominated the restarted race on Monday, leading most of the way and winning by a massive seven full laps over Cecil Gordon. Richard Petty finished third, followed by James Hylton in fourth and David Sisco in fifth. Pearson earned $15,425 for the victory — his 85th career NASCAR win.
The win was Pearson’s second straight at Dover. Following the race, Richard Petty extended his points lead to 378 points over Darrell Waltrip.
