The 321st Armored Cavalry Regiment (321st ACR) was a Virginia-based reconnaissance unit of the United States Army Organized Reserve Corps, which briefly existed after World War II.
It was constituted in 1948, partially organized from existing units in 1949, and disbanded in 1952.
The 1st Battalion was redesignated from the 317th Mechanized Cavalry Reconnaissance Squadron, constituted on 8 November 1946 in the Organized Reserves and activated on 19 November at Lynchburg.
[1] In mid-November 1949, the assault gun company absorbed the men of a battery of the 780th Field Artillery Battalion.
The 321st ACR did not inherit the lineage of the prewar 321st Cavalry Regiment, and was not authorized a coat of arms or distinctive unit insignia.