Courtesy misspeedway.com website:
“The track is nestled on more than 1,400-plus acres in the Irish Hills of southeastern Michigan. Groundbreaking took place on September 28, 1967. Over 2.5 million yards of dirt were moved to form the D-shaped oval designed by Charles Moneypenny, who previously designed the 2.5-mile Daytona International Speedway. The original layout included infield and exterior roads, which could be combined to form a single 3.1-mile interior/exterior road course, or divided into separate 1.9-mile interior/exterior road courses. The road courses were designed by Formula One great Stirling Moss and are still used on a limited basis for passenger car testing by area law enforcement agencies. The last interior road course race was held in 1984, and the last time the exterior road course was used was in 1973.”
