On August 12, 1918, the Post Office Department began regular U.S. Air Mail Service from College Park Airfield to New York City using civilian pilots and aircraft. The route ran from College Park, Maryland, to Bustleton Field outside Philadelphia, Pennsylvania, and then to Belmont Park on Long Island, New York. Service began with World War I surplus Curtiss Jennys and DeHavilland DH-4s provided by the U.S. Army, and postal officials also ordered six airplanes from the Standard Aircraft Company designed to carry up to 500 pounds of mail. Between 1918 and 1921, College Park Airport played a vital role in the airmail experiment as a training facility and as a place for developing the equipment, personnel, and administrative systems needed to sustain a transcontinental airmail system. In 1921, the Postal Service closed the College Park airmail station to focus on routes where airmail was superior in speed and cost to the railroad. Airmail ultimately led to the birth of America’s commercial airlines and the travel industry, and after airmail left, College Park airfield remained in operation as researchers, inventors, and businesses worked to improve aviation.