After the reconstruction era, North Carolina had become a one-party state, dominated by the Democratic Party. The state mainly continued with an economy based on tobacco, cotton textiles and commodity agriculture. Large towns and cities remained in few numbers. However, a major industrial base emerged in the late 19th and early 20th century, in the counties of the Piedmont Triad, based on cotton mills established at the fall line. Railroads were built to connect the new industrializing cities. The state was the site of the first successful controlled, powered and sustained heavier-than-air flight, by the Wright brothers, near Kitty Hawk on December 17, 1903. In the first half of the 20th century, many African Americans left the state to go North for better opportunities, in the Great Migration. Their departure changed the demographic characteristics of many areas.