Marble Hill is the neighborhood which makes up the northernmost part of the Borough of Manhattan in NYC. Although it is politically part of Manhattan, because of the re-routing of the Harlem River it is located on the mainland contiguous to the Bronx, not on Manhattan Island. Because of its geography, Marble Hill is often associated with the Bronx; for instance, it is part of two of the Bronx's Community Board Districts.  Broadway is the area’s primary thoroughfare. At the end of the 20th century, national retailers opened many outlets in the neighborhood.