Politically a part of Manhattan and New York County, Marble Hill became an island in the Harlem River when it was separated from the island of Manhattan by the construction of the Harlem Ship Canal in 1895. In 1914, the Harlem River was filled in on the north side of Marble Hill, connecting it to the North American mainland and the Bronx.[3] Because of this change in geography, Marble Hill is often associated with the Bronx and is part of two of the latter's Community Board Districts.
After an increase in ship traffic in the 1890s, the United States Army Corps of Engineers determined that a canal was needed for a shipping route between the Hudson and Harlem rivers. In 1895, the construction of the Harlem River Ship Channel rendered Marble Hill an island bounded by the canal to the south and the original course of the Harlem River to the north.[6] The Greater New York Charter of 1897 designated Marble Hill as part of the Borough of Manhattan. Effective January 1, 1914, by an act of the New York State Legislature Bronx County was created, but Marble Hill remained as part of New York County. Later in 1914, the old river was filled in, physically connecting Marble Hill to the Bronx and the rest of the North American mainland.