Constituted 23 July 1918 in the National Army as Headquarters, 100th Division. Organized in October 1918 at Camp Bowie, Texas. Demobilized 30 November 1918 at Camp Bowie, Texas. Reconstituted 24 June 1921 in the Organized Reserves as Headquarters, 100th Division. Organized 27 September 1921 at Charleston, West Virginia. Location changed 29 February 1924 to Huntington, West Virginia; on 6 August 1937 to Charleston, West Virginia. Redesignated 23 February 1942 as Division Headquarters, 100th Division. Ordered into active military service 15 November 1942 and reorganized at Fort Jackson, South Carolina as Headquarters, 100th Infantry Division. Inactivated 10 January 1946 at Camp Patrick Henry, Virginia.