The physical roots of this telephone anomaly trace back to 19th-century commercial navigation demands. Marble Hill was once the northernmost spur of Manhattan Island, surrounded to the north and west by the looping, shallow waters of Spuyten Duyvil Creek. In the late 1800s, commercial tugs and barges shipping materials along the Hudson River faced treacherous journeys around the northern tip of the island to reach Long Island Sound.
To solve this shipping bottleneck, the U.S. Army Corps of Engineers carved the Harlem River Ship Canal directly through the bedrock south of Marble Hill. When the canal opened to commercial traffic in 1895, it blasted a deep-water trench that severed the ridge from the rest of Manhattan Island, turning Marble Hill into an artificial island trapped between the canal and the old creek.
Nineteen years later, urban real estate developers and municipal engineers filled in the original loop of Spuyten Duyvil Creek with subway-excavation rubble and landfill. By 1914, the water that separated Marble Hill from the Kingsbridge neighborhood in the Bronx was gone. The land had physically merged with the North American mainland, but its political allegiance never followed the soil.
