Rockland County is the southernmost county on the west side of the Hudson River. The county's population, as of the 2010 census, was 311,687, increasing by 4.6% to a 2015 Census estimate of 326,037, making it the third most densely populated county outside of New York City within New York State (after Nassau and neighboring Westchester counties, respectively). The county seatis New City. Although Rockland County does not directly border any New York City boroughs, it lies only 9 miles northwest of the city at their closest points, and is accessible through 10 exits on the New York State Thruway. The name derives from "rocky land", as the area was described by early Dutch and English settlers.
Rockland County is the smallest county by area in New York State outside ofNew York City. It comprises five towns and nineteen incorporated villages, with numerous unincorporated villages (sixteen) and hamlets.
The county's elevations range from 1,283 feet (391 m) atop Rockhouse Mountain to sea level along the Hudson River. Approximately 30% of Rockland County is devoted to parkland, belonging to either the five towns, incorporated villages, the state, or the county. These parks provide walking and hiking trails, ball fields, dog runs, historic sites, ponds, streams, salt marshes, and equestrian trails. Some popular state parks include Bear Mountain State Park on the northernmost tip of the county, Harriman State Park also along the county's northern boundary, and Nyack Beach State Park along the Hudson River, with trails connecting to Rockland Lake State Park.