Sports-car racing crossed the pond to the US in the 1950s, as prosperous Americans bought European-made sports cars. In Europe, commercially built tracks proliferated—but with the multiple curves of the traditional road courses. Upper-middle-class and wealthier US sports-car racers wanted the same kind of twisting courses, and these men laid out many of the earliest on abandoned Air Force fields from World War II. In the US and Europe, many classes of sports-car racing developed, with most classes based on production European cars and.racing under rules codified for a given range of engine size and total car weight, and separate classes for street-legal production cars and for all-out, purpose-built race cars run by very wealthy owners only on tracks.

The regionalized and fairly democratic Sports Car Club of America (SCCA) regulates the sports-car racing of wealthy amateur racers in their own interest. Professional sports-car racing is dominated by manufacturers, through the International Motor Sports Association (IMSA) and recently the “Le Mans Series,” owned by Don Panoz, the race-car builder and owner of the premier sports-car track, in Sebring, FL. Yet the codified rules, and classes, never stop changing. Some organizing bodies of professionally run, ‘prototype’ sports cars have failed during the last several decades, due to inability to generate enough ticket-buying fans to economically survive. Such bodies, if they have little money, have little power to set uniform rules, and so new bodies arise funded by such as Panoz which are free to set new rules.