It was a huge deal in the early 1900s because it was a road that connected Chicago and California. But it stopped being nearly as important once other roads began being built and our highway system came into place. Early on, its dominance as a cross-country road allowed businesses to prosper along it because people had to use it to make that kind of trip. Ever since the passage of the Interstate Highway Act of 1956, Route 66 has gradually become less important.