The regiment was constituted on 15 October 1921 in the Organized Reserves, part of the
66th Cavalry Division's
162nd Cavalry Brigade in the
Seventh Corps Area. On 14 November it was transferred to the
Ninth Corps Area. It was initiated (activated) on 4 March 1922 with headquarters at
San Francisco, 1st Squadron at
Sacramento, and 2nd Squadron at
Portland with two troops in Washington. In 1924, the headquarters was relocated to
San Diego, the Oregon and Washington units were inactivated, and the 1st and 2nd Squadrons moved to
Los Angeles. In July 1929, the 323rd was reorganized as a three-squadron regiment. On 28 January 1930, the entire regiment was relocated to San Diego. Between 14 and 22 March 1933, many unit personnel participated in relief operations in response to the
1933 Long Beach earthquake. In 1934, the entire regiment was relocated to Los Angeles. The 323rd conducted regular equestrian training on the horses of Troop B,
11th Cavalry Regiment at
Camp L.J. Hearn between 1924 and 1929. It conducted summer training at the
Presidio of Monterey with the 11th Cavalry. As an alternate form of training, the regiment provided cavalry training to civilians under the
Citizens' Military Training Camp program at the Presidio of Monterey. Its designated mobilization training station was
Fort Francis E. Warren, Wyoming. Upon moving to Los Angeles, future United States President
Ronald Reagan joined the regiment's Headquarters Troop as a
second lieutenant on 18 June 1937. After the United States entered
World War II, the regiment was converted into the 549th Signal Aircraft Warning Regiment on 30 January 1942. The regiment was disbanded on 11 November 1944. == Commanders ==