The Bronx ( BRONKS) is the northernmost of the five boroughs of New York City, coextensive with Bronx County, in the U.S. state of New York. The borough shares a land border with Westchester County, New York to its north; to its south and west, the New York City borough of Manhattan lies across the Harlem River; and to its south and east is the borough of Queens, across the East River. The Bronx, the only New York City borough located primarily on the U.S. mainland, has a land area of 42 square miles (109 km2) and a population of 1,472,654 at the 2020 census. It has the fourth-largest area, fourth-highest population, and third-highest population density of the boroughs.
The Bronx is divided by the Bronx River into a hillier section in the west, and a flatter eastern section.