Washington Heights is bounded to the south by 155th Street and to the north by Fairview Avenue and runs from the Harlem River on the east to the Hudson River on the west. Inwood is the northern tip of the island, everything lying north of Fairview Avenue. The two neighborhoods are often lumped together as one because administratively they make up Manhattan Community District 12. Marble Hill is the landlocked section of Manhattan and is now physically connected to the Bronx. It was separated from the rest of Manhattan when the Harlem River Ship Canal was dug and the Spuyten Duyvil Creek was filled in..