Plymouth County is a county in the U.S. state of Massachusetts, south of Boston. As of the 2020 census, the population was 530,819. Its county seats are Plymouth and Brockton. In 1685, the county was created by the Plymouth General Court, the legislature of Plymouth Colony, predating its annexation by the Massachusetts Bay Colony. Plymouth County is part of the Boston–Cambridge–Newton, MA–NH Metropolitan Statistical Area. Geography According to the U.S. Census Bureau, the county has a total area of , of which is land and (40%) is water. It is the third-largest county in Massachusetts by total area. Adjacent counties The towns of Hingham and Hull in Plymouth County extend north of Norfolk County and face onto Massachusetts Bay, sharing a northern water boundary with Suffolk County. Norfolk County (north) Barnstable County (southeast) Bristol County (west) National protected area Boston Harbor Islands National Recreation Area (part) Massasoit National Wildlife Refuge Major highways Demographics 2000 census At the 2000 census there were 472,972 people, 168,361 households, and 122,398 families in the county. The population density was . There were 181,524 housing units at an average density of . The racial makeup of the county was 88.70% White, 4.56% Black or African American, 0.21% Native American, 0.92% Asian, 0.02% Pacific Islander, 3.06% from other races, and 2.52% from two or more races. 2.44%. were Hispanic or Latino of any race. 28.0% were of Irish, 12.8% Italian, 10.6% English and 5.1% American ancestry, 90.1% spoke English, 2.5% Spanish, 2.3% Portuguese, 1.5% French Creole and 1.0% French as their first language. Of the 168,361 households 36.30% had children under the age of 18 living with them, 57.00% were married couples living together, 11.90% had a female householder with no husband present, and 27.30% were non-families. 22.20% of households were one person and 9.00% were one person aged 65 or older. The average household size was 2.74 and the average family size was 3.23. The age distribution was 26.80% under the age of 18, 7.20% from 18 to 24, 30.40% from 25 to 44, 23.90% from 45 to 64, and 11.80% 65 or older. The median age was 37 years. For every 100 females, there were 95.00 males. For every 100 females age 18 and over, there were 91.30 males. The median household income was $55,615 and the median family income was $65,554 (these figures had risen to $70,335 and $82,560 respectively as of a