1920s

The Federal Aid Highway Act of 1921 provided funds and resources for the construction of highways across the US, and by the end of the decade some 23 million Americans were registered drivers. Most vehicles manufactured in the United States were constructed on assembly lines, and Ford, General Motors, and Chrysler together were responsible for 80% of the automotive industry's output. In Europe, vehicles continued to be built by hand and were largely purchased by members of the upper classes like the Bentley Boys, who won Le Mans four consecutive years from 1927-1930.