Brooklyn (/ˈbrʊklɪn/) is a borough of New York City, coextensive with Kings County, in the U.S. stateof New York. Kings County is the most populous county in the State of New York, and the second-most densely populated county in the United States, behind New York County (Manhattan).Brooklyn is also New York City's most populous borough, with 2,736,074 residents in 2020.