The 1970 Mason-Dixon 300 was a 300-lap NASCAR Grand National Series race held on May 3, 1970, at Dover Downs International Speedway in Delaware. The second running of the event drew an attendance of 20,000 fans for the 36-car field on the high-banked one-mile concrete oval.
Bobby Isaac won the pole position with a speed of 129.538 mph. The race was slowed by four cautions for 27 laps and was ultimately won by Richard Petty in his famous #43 Plymouth Superbird. Petty took the victory with an average speed of 112.103 mph, beating Bobby Allison by 27 seconds. Charlie Glotzbach finished third, followed by David Pearson in fourth and Benny Parsons in fifth. Bobby Isaac finished sixth and James Hylton seventh. Petty earned $6,195 for the win.
This victory was Petty’s second consecutive win in the Mason-Dixon 300 and further demonstrated the Superbird’s strength on the fast Dover track. After the race, Bobby Isaac maintained a 41-point lead over James Hylton in the championship standings with seven races remaining in the season.
