The overall post population is estimated at about 71,000, of which are almost 42,000 soldiers. The rest are family members living on post, employees of the Army Air Force Exchange Service, volunteers and other employees. The 1st Cavalry Division is staffed with more than 17,000 soldiers, while the 4th Infantry Division has more than 11,000. The 13th Corps Support Com-mand has about 5,600, the 3rd Signal Brigade has 1,600 and the 89th Military Police Brigade has almost 1,000. Also: the Headquarters Command has about 850 soldiers; the 3rd Personnel Group with almost 800; the 21st Cavalry Brigade with more than 300; the 21st Replacement Company with more than 150; and other units at Fort Hood have about 1,200 soldiers. There are more than 37,000 enlisted soldiers and more than 3,700 officers. In addition, more than 300 Air Force airmen are on duty at the post.