|Official name Southeastern 500|
|Date March 20, 1966 (1966-March-20)|
Location Bristol International Speedway, Bristol, Tennessee
Course Permanent racing facility 0.500 mi (0.800 km)
Distance 500 laps, 250.0 mi (400.0 km)
Weather Temperatures reaching up to 69 °F (21 °C); wind speeds up to 14 miles per hour (23 km/h)
The 1966 Southeastern 500 was a NASCAR Grand National Series (now Monster Energy NASCAR Cup Series) event that was held on March 20, 1966, at Bristol International Speedway in the Bristol, Tennessee.
The transition to purposely-built racers began in the early 1960s and occurred gradually over that decade. Changes made to the sport by the late 1960s brought an end to the "strictly stock" vehicles of the 1950s; most of the cars were trailered to events or hauled in by trucks.
Five hundred laps were done on a paved oval track spanning 0.500 miles (0.805 km). The total time of the race was three hours, twenty-four minutes, and twenty-six seconds. There were seven cautions for 92 laps. Speeds were: 69.952 miles per hour or 112.577 kilometres per hour and 86.248 miles per hour or 138.803 kilometres per hour for the pole position speed (accomplished by David Pearson). Dick Hutcherson defeated Paul Lewis by outlapping him more than four times; resulting in Ford's 200th win. The Ray Nichels team had also used the #9 for Larry Frank's entry at Daytona earlier in the season. They also had Don White run multiple car numbers in the 1966 season, so they weren't always consistent with them.
Richard Petty had an injured finger and couldn't participate in this race; Jim Paschal had to take over as the relief driver.
Twenty-five thousand fans saw thirty-two drivers start a race that only seven would complete. Attrition levels were worse in this Bristol race than it is in the 2010 NASCAR Cup Series season; a rare instance where lower speeds on a track are more dangerous than faster speeds. By contrast, the 2010 Food City 500 would see an average speed of 79.618 miles per hour or 128.133 kilometres per hour and a pole position speed of 124.63 miles per hour or 200.57 kilometres per hour with only eight drivers not being able to complete the race.
The total winnings for the race were $21,735 in American dollars ($160,437.74 when inflation is taken into effect).
† signifies that the driver is known to be deceased
* Driver failed to finish race