U.S.S. "Illinois" and Wharf: Armory for Naval Reserves, July 2, 1937. The USS Prairie State docked at the 135th Pier on the Hudson River was the nation's largest floating armory. The 375-foot houseboat had been a naval battleship, the USS Illinois, from 1901 until 1920. In 1924, it was disarmed and converted into an armory with the large, barn-like shed built on the hull. The USS Prairie State remained until 1951, when it was relocated to 25th Street on the East River and eventually scrapped. In 1991, the City opened the North River Waste Water Treatment plant on this site.