Soon after motor vehicles were invented they were raced. Initially the contests were held on open roads, often from city to city. The very first I have been able to find documented involved two steam-driven tractors chugging between Madison and Green Bay, Wisconsin, on July 16, 1878. The problems of open-road racing were that the opportunities for spectators, who saw the cars go by only once, were limited, and concerns about safety. Between WWI and WWII, most (but not all) racing in the U.S. took place on ovals. After WWII, due to growing enthusiasm for sports cars, road racing was re-established. Here’s how it happened:
As an aside, it’s interesting to note that three of the premier U.S. road-racing courses—Watkins Glen, Road America and Laguna Seca—developed in similar fashions. Also interesting is that these three represent the three major sections of the country: east, middle and west.