In the early 1900s, American roads were often little more than dirt trails. It limited long-distance motorized travel to only the heartiest adventurers. By the 1920s, though, the American Association of State Highway Officials was working to change that. With the adoption of this new system, paved roads were reaching more parts of the country than ever before. The highways drew increasing numbers of vacationing Americans, and by the 1930s, over 20 million privately-owned cars and motorcycles were zooming down the road.