Camp Mabry, in northwestern Austin, was established in the early 1890s as a summer encampment of the Texas Volunteer Guard, a forerunner of the Texas National Guard. In 1891 a citizens' committee in Austin began looking for a place for the volunteer guard to train. In 1892 they chose an eighty-five-acre site three miles northwest of the Capitol. The guardsmen chose to name the new camp in honor of Woodford Haywood Mabry, adjutant general of Texas from January 1891 to May 1898. In 1909 the size of the camp was greatly increased by the addition of 200 acres that the federal government purchased for the state for use in training the national guard. Other gifts brought the size of the encampment to 400 acres by 1911.
Since its establishment Camp Mabry has served in a variety of capacities. It was used as a mobilization area during the Spanish-American War. The state arsenal building was built there in 1915, and all military stores were moved from the state Capitol to the new facility. During World War I the United States Army used the camp as a training site and built several barracks and administration buildings. The army also used the camp as an engine-rebuilding station during the war. When the Texas National Guard was called into federal service during World War II, Camp Mabry served as Headquarters for the Texas Defense Guard, the remaining state militia. Camp Mabry served as a training ground for the Texas Department of Public Safety and the Texas Rangers, as well as the national guard, until 1953. The state adjutant general's office was moved to Camp Mabry in 1954, and the Texas National Guard State Officer Candidate School was established there in 1959. A historical marker acknowledging the contribution of Camp Mabry was dedicated in December 1972.
In the mid-1980s the size of the Camp Mabry site was just over 375 acres, and the building space was 700,000 square feet. The various offices at Camp Mabry employed 800 people. The Texas National Guard Academy opened at Camp Mabry in June 1984. Also located on the post are the headquarters of the Texas Air National Guard, the Texas State Guard, the United States Property and Fiscal Office, the Texas National Guard Armory Board, the Headquarters Armory of the Forty-ninth Armored Division, a clinic, a parachute packing and storage facility, and numerous supply and warehouse facilities.
Camp Mabry observed its 100th anniversary on Texas Armed Forces Day in May 1992. In addition to battle reenactments and displays, the celebration included an informal opening of the Texas Military Forces Museum, which was completed later that year.