The first transcontinental flight across the U.S. within a single day (24-hour period) was made by Lt. Jimmy Doolittle on September 4, 1922. Flying a de Havilland D.H.4B (shown in photo), Doolittle took off from Pablo Beach, Florida and landed at Rockwell Field near San Diego, California, covering a distance of 2,163 miles in 21 hours, 20 minutes flying time. He made one refueling stop at Kelly Field near San Antonio, Texas.

Credits - U.S. Air Force Museum