Fort MacArthur is a former United States Army installation in San Pedro, Los Angeles, California (now the port community of Los Angeles). A small section remains in military use as a housing and administrative annex of Los Angeles Air Force Base. The fort is named in honor of Lieutenant General Arthur MacArthur. His son, Douglas MacArthur, would later command American forces in the Pacific during World War II.
In 1888 President Grover Cleveland designated an area overlooking San Pedro Bay as an unnamed military reservation intended to improve the defenses of the expanding Los Angeles harbor area.