- Your Ad Here Rockland County is a county located in the U.S. state of New York. As of the 2016 census, the population was 326,780. The county seat is New City. Sponsored Links History The name comes from "rocky land", an early description of the area given by settlers. The area that would become Rockland County was originally inhabited by Algonquian-speaking Native Americans, including Munsees, or Lenni Lenape. |