The population count of Plymouth County, MA was 492,313 in 2009. The population count of Worcester County, MA was 795,726 in 2009. The population count of Hillsborough County, NH was 402,576 in 2009. The population count of Rockingham County, NH was 296,680 in 2009.
Population
Population Change
Above charts are based on data from the U.S. Census American Community Survey | ODN Dataset | API -