Rockland County is the southernmost county on the west side of the Hudson River in the U.S. state of New York and part of the New York-Newark-Jersey City, NY-NJ-PA Metropolitan Statistical Area. The county's population, as of the 2010 census, was 311,687, increasing by 3.9% to a 2014 Census estimate of 323,866. The county seat is New City. The name derives from "rocky land", as the area was described by early Dutch and English settlers.
- Rockland County, New York on Wikipedia