Rockland County is the southernmost county on the west side of the Hudson River in the U.S. state of New York, part of the New York City metropolitan statistical area. It is a suburb of New York City that is about from the Bronx at their closest points. The county's population, as of the 2010 United States Census, was 311,687, increasing to a 2019 Census estimate of 325,789, making it the third-most densely populated county outside New York City within New York (after Nassau and neighboring Westchester Counties, respectively). The county seat is New City. Rockland County is accessible via the New York State Thruway, which crosses the Hudson to Westchester at the Tappan Zee Bridge ten exits up from the Bronx, as well as the Palisades Parkway five exits up from the George Washington Bridge. The county's name derives from "rocky land", as the area has been aptly described, largely due to the Hudson River Palisades.