The Bronx is the northernmost of the five boroughs of New York City, within the U.S. state of New York. It is geographically south of Westchester County; north and east of the island and borough of Manhattan to the south and west across the Harlem River; and north of the borough of Queens, across the East River. Of the five boroughs, the Bronx is the only one that has the majority of its area on the U.S. mainland and, with a land area of 42 square miles and a population of 1,455,720 in 2016, has the fourth-largest land area, the fourth-highest population, and the third-highest population density. Since 1914, the Bronx has had the same boundaries as Bronx County, a county of New York and the third most densely populated county in the United States.The Bronx is divided by the Bronx River into a hillier section in the west, closer to Manhattan, and a flatter eastern section, closer to Long Island.