Fort Lowell was a United States Army post active from 1873 to 1891 on the outskirts of Tucson, Arizona. Fort Lowell was the successor to Camp Lowell, an earlier Army installation. The Army chose a location just south of the confluence of the Tanque Verde and Pantano creeks, at the point where they form the Rialto River, due to the year-round supply of water during that period. The Hohokam natives had chosen the site centuries earlier, presumably for the same reason.