Despite the depression, 1930s saw a boom in innovation and growth, riding on the tailwind of scientific and and technological innovation from the 1920s. Aviation, plastics, movies, appliances, and a bunch of other industries got going in that time. By 1939 three-times as many people had cars in US as they did in 1929. It all got badly mismanaged, but the basis for a booming economy were all there. Today, on the other hand, we are doing a fine job managing the economy, but we don't have such a strong tailwind to propel our growth.