The Santa Ana Army Air Base was created in 1941 to be the command center for army aviation personnel in training on the west coast of the United States.

It was located in southern California, in Orange County, in an area that would later become Costa Mesa. At the time of its construction, the area was mainly bean and tomato fields. Originally just over 400 acres, it grew during the war to encompass over 1300 acres.

It provided pre-flight training to the wartime surge in Army aircrews. It also oversaw the primary, basic, and advanced flight training provided at other military bases and civilian contractor airfields throughout the west.

The base was at maximum capacity in the fall of 1943, with 26,000 servicemen. By the time of its closure as a training base, it had seen about 150,000 aviation personnel. Just over half of those were pilots in training. Most of the remainder were bombardiers and navigators.

In May of 1944, aviation training at the base ceased. The output of the three large training commands (East Coast, South Coast and West Coast) had produced more pilots, bombardiers and navigators than the Air Force could possibly use, and there were more than enough personnel in the aviation pipeline.

In 1946, the base was deactivated and the land gradually sold or transferred. The eastern portion of the base is now the John Wayne Airport, while most of the western part of the land is now the Orange County Fairgrounds.