Massachusetts County Map

Most populous counties

The five most populous counties are home to 68.7% of Massachusetts’s 7,029,917 residents (2020 Census).

1. Middlesex County (Lowell and Cambridge): 1,632,002, 23.2% of the state
2. Worcester County (Worcester): 862,111, 12.3% of the state
3. Essex County (Salem and Lawrence): 809,829, 11.5% of the state
4. Suffolk County (Boston): 797,936, 11.4% of the state
5. Norfolk County (Dedham): 725,981, 10.3% of the state

Middlesex County, which takes in Cambridge, Lowell and many suburbs west and north of Boston, has nearly twice the population of second-place Worcester County. Nantucket County is the least populous, with 14,255 residents.

Largest and smallest counties

Worcester County, in the middle of the state, is the largest county at 1,510.7 sq mi of land, followed by Berkshire County (926.9 sq mi) in the far west. Nantucket County is the smallest, with 46.2 sq mi of land, and Suffolk County is next at 58.3 sq mi. Water changes the picture on the coast: Barnstable County covers 1,305.5 sq mi in total but only 394.2 sq mi of land.

How counties work in Massachusetts

Local government in Massachusetts is run mainly by its 351 cities and towns, not by counties. Since 1997 the state has abolished the county governments of Berkshire, Essex, Franklin, Hampden, Hampshire, Middlesex and Worcester counties; these counties still exist as geographic units and court districts, and their sheriffs and registries of deeds still operate.

• Suffolk County is made up of Boston, Chelsea, Revere and Winthrop, and the City of Boston handles most county matters.
• Nantucket County covers the same island area as the Town of Nantucket.
• Dukes County is Martha’s Vineyard plus the Elizabeth Islands.
• Barnstable County is Cape Cod.

Some counties list two seats (shire towns), where county courts and offices are split between two places: Essex County (Salem and Lawrence), Middlesex County (Lowell and Cambridge), Plymouth County (Plymouth and Brockton).