The 309th Cavalry Regiment was a cavalry unit of the United States Army 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 North Carolina Organized Reserve unit during the interwar period, and later moved to Georgia in the early 1930s. It was converted into a signal aircraft warning regiment after the United States entered World War II.