Two structures mark the entrance to the Niagara River - the city of Buffalo water intake and the abandoned Horseshoe Reef Light. The Horseshoe Reef Light, the dark metal structure atop a concrete base, was established in 1856 after Canada and England transferred an acre of territory in Canadian waters to the United States. The lighthouse actually stands on Middle Reef, more centrally located than Horseshoe Reef; the international boundary was moved by a 1908 treaty to put the lighthouse in American waters. Two keepers alternated on duty at the lighthouse, which was considered one of the loneliest stations in the district, despite the nearness of a major city. The Buffalo crib intake, the round red-roofed structure, was built in the Emerald Channel nearby and its light established in 1908, and Horseshoe Reef Light was abandoned in 1920.