Geography of New York City Bronx and Manhattan from Northern New Jersey. The Harlem River, another tidal strait between the East and Hudson Rivers, separates Manhattan from the Bronx. The boroughs of New York City straddle the border between two geologic provinces of eastern North America. Brooklyn and Queens, located on Long Island, are part of the eastern coastal plain. Long Island is a massive moraine which formed at the southern fringe of the Laurentide Ice Sheet during the last Ice Age. The Bronx and Manhattan lie on the eastern edge of the Newark Basin, a block of the Earth's crust which sank downward during
Manhattan of Greater New York", Manhattan and the Bronx, though still one county, were established as two separate boroughs. On January 1, 1914, the New York State Legislature created Bronx County, and New York County was reduced to its present boundaries. The construction of the New York City Subway, which opened in 1904, helped bind the new city together, as did additional bridges to Brooklyn. In the 1920s Manhattan experienced large arrivals of African-Americans as part of the Great Migration from the southern United States, and the Harlem Renaissance, part of a larger boom time in the Prohibition era that included