The 303rd Armored Cavalry Regiment (303rd ACR) was a New York-based reconnaissance unit of the United States Army Organized Reserve Corps that briefly existed after World War II.  It traced its history back to the 303rd Cavalry Regiment, a reserve unit that existed during World War I and the interwar period. It was activated in early 1918 but broken up in the middle of the year to form new artillery units. The unit was recreated as a New York Organized Reserve unit during the interwar period, and was disbanded after the United States entered World War II.