Resident Population in Plymouth County, MA was 535.30800 Thous. of Persons in January of 2023, according to the United States Federal Reserve. Historically, Resident Population in Plymouth County, MA reached a record high of 535.30800 in January of 2023 and a record low of 333.31400 in January of 1970. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Plymouth County, MA - last updated from the United States Federal Reserve on May of 2024.