<Tr> <Th> Area code (s) </Th> <Td> 718 / 347 / 929, 917 </Td> </Tr> <Tr> <Th> Website </Th> <Td> Official website of the Bronx Borough President </Td> </Tr> <P> The Bronx (/ brɒŋks /) is the northernmost of the five boroughs of New York City within the U.S. state of New York . It is south of Westchester County; north and east of Manhattan, across the Harlem River; and north of Queens, across the East River . Since 1914, the borough has had the same boundaries as Bronx County, the third-most densely populated county in the United States . </P> <P> The Bronx has a land area of 42 square miles (109 km) and a population of 1,471,160 in 2017 . Of the five boroughs, it has the fourth - largest area, fourth - highest population, and third - highest population density . It is the only borough predominantly on the U.S. mainland . </P>

What county is the bronx in new york