The 114th Machine Gun Battalion and 105th Trench Mortar Battery were demobilized on 10 April 1919 at Fort Oglethorpe, Georgia.

The regimental headquarters was successively relocated to Nashville, Tennessee, on 25 January 1926, and back to Chattanooga on 28 October 1936.

Concurrently, the 3rd Squadron and the Machine Gun Troop were withdrawn from North Carolina and allotted to Tennessee, making the 109th a wholly Tennessee-based unit.

Troop G was called up to preserve order at the trial of an African American prisoner in Halifax, North Carolina, from 23 to 24 June 1927.

The 3rd Squadron performed strike duty at textile mills at Gastonia, North Carolina, in April 1929.

After the Japanese attack on Pearl Harbor, the regiment proceeded to Camp Roberts, California, where on 27 December 1941 it was assigned to the II Armored Corps.

It was reorganized and federally recognized on 14 November 1946 in southern Tennessee, with headquarters at Chattanooga, and assigned to the 30th Infantry Division.