Rockland is a town in Plymouth County, Massachusetts, United States. The population was 17,803 at the 2020 census. As of December 31, 2009, there were 11,809 registered voters in the community. Rockland was a part of territory given to one Timothy Hatherly in a land grant, later known as the Hatherly Grant, in 1654. It was then populated by European se…Rockland is a town in Plymouth County, Massachusetts, United States. The population was 17,803 at the 2020 census. As of December 31, 2009, there were 11,809 registered voters in the community. Rockland was a part of territory given to one Timothy Hatherly in a land grant, later known as the Hatherly Grant, in 1654. It was then populated by European settlers as a northeastern region of the neighboring town Abington in 1673. The town separated and incorporated as Rockland on March 9, 1874. It is named for the town's rocky nature, which was better suited for mills and industry than for farming. During King Philip's War, the town was the site of an encampment during his raids on the town of Scituate.