Since founding Davis-Douglas Company in 1920, Douglas has been associated with innovative aircraft manufacture. Through mergers and takeovers, one constant has been cutting-edge design. In 1924 the first planes to fly around the world were the Douglas World Cruisers. In 1940s the Skystreaks, Skyrockets and Skyrays protected America's hold on world airspeed records against competition from Britain's Hawker and Supermarine companies. Douglas was one of the first manufacturers to exploit the potential of the commercial market with its DC series. The DC-3 and its derivatives still qualify as the most successful air transport with more than 10,000 built.