- Brooklyn is a borough of New York City located at the westernmost end of Long Island in the State of New York. Formerly an independent city, the borough is coextensive with Kings County, one of twelve original counties established under British rule in 1683 in the then Province of New York. As of the 2020 United States census, the population stood at 2,736,074, making it the most populous of the five boroughs of New York City, the most populous county in the State of New York, and the ninth most populous county in the United States. In 2022, the population density of Brooklyn was recorded at 37,339.9 inhabitants per square mile (14,417.0/km2), making it the second most densely populated county nationwide, behind only Manhattan (New York County). Had Brooklyn remained an independent city, it would today be the fourth most populous American city after New York, Los Angeles, and Chicago.