The range, speed and lifting capacity of aircraft were transformed through technological innovation during the war, allowing the first practical air mail services to finally become a reality when the war ended. For instance, the first regularly scheduled airmail service in the United States was inaugurated on May 15, 1918. The route, which ran between Washington, D.C., and New York City, with an intermediate stop in Philadelphia, Pennsylvania, was designed by aviation pioneer Augustus Post. In 1925, the U.S. Postal service issued contracts to fly airmail between designated points. In 1931, 85% of domestic airline revenue was from airmail.