airmail, transport of mail by airplanes. Demonstration flights that showed the feasibility of carrying mail by air were made in Great Britain and in the United States in 1911. In the United States, after money for experimentation was appropriated by Congress in 1918, the first regular airmail service for carrying civilian mail began on May 15, 1918. Army pilots and army equipment were used. The first flight was from Washington, D.C., to New York City; although the pilot got lost and never completed the trip, regular airmail service was soon established. The Post Office Dept. took over operation of the line in 1920, but in 1921 the line was discontinued. In May, 1920, the transcontinental route from New York City to San Francisco was completed. On July 1, 1924, coast to coast service by air was scheduled for the first time (before then the mail had been transferred to trains at night). Transpacific airmail was introduced in 1935 and transatlantic airmail in 1939. Airmail service now extends throughout the world.