The histories of March Field and Southern California have been intertwined for nearly a century. Anticipating the need to build up military forces prior to America's entry into World War I, the Army directed officers stationed in the Los Angeles area to survey Riverside's Alessandro plain for suitability as a flying training field (a two-day trip by horseback) in late 1917. The base first opened its gates in March 1918, making it one of the three oldest installations in the Air Force today, along with Randolph AFB in Texas and Langley AFB in Virginia.