| | Barnstable County | MA | 25001 | | Barnstable Town, MA 12700 | Boston-Worcester-Providence,
MA-RI-NH-CT 148 | Central | metro county (urban) | recreation | https://maps.google.com/?q=BarnstableCounty+MA |
| | Berkshire County | MA | 25003 | | Pittsfield, MA 38340 | | Central | metro county (urban) | recreation | https://maps.google.com/?q=BerkshireCounty+MA |
| | Bristol County | MA | 25005 | | Providence-Warwick, RI-MA 39300 | Boston-Worcester-Providence,
MA-RI-NH-CT 148 | Central | metro county (urban) | nonspecialized | https://maps.google.com/?q=BristolCounty+MA |
| | Essex County | MA | 25009 | Cambridge-Newton-Framingham,
MA 15764 | Boston-Cambridge-Newton,
MA-NH 14460 | Boston-Worcester-Providence,
MA-RI-NH-CT 148 | Central | metro county (urban) | nonspecialized | https://maps.google.com/?q=EssexCounty+MA |
| | Hampden County | MA | 25013 | | Springfield, MA 44140 | Springfield-Amherst
Town-Northampton, MA 521 | Central | metro county (urban) | nonspecialized | https://maps.google.com/?q=HampdenCounty+MA |
| | Hampshire County | MA | 25015 | | Amherst Town-Northampton,
MA 11200 | Springfield-Amherst
Town-Northampton, MA 521 | Central | metro county (urban) | federal/state
government-dependent | https://maps.google.com/?q=HampshireCounty+MA |
| | Middlesex County | MA | 25017 | Cambridge-Newton-Framingham,
MA 15764 | Boston-Cambridge-Newton,
MA-NH 14460 | Boston-Worcester-Providence,
MA-RI-NH-CT 148 | Central | metro county (urban) | nonspecialized | https://maps.google.com/?q=MiddlesexCounty+MA |
| | Norfolk County | MA | 25021 | Boston, MA 14454 | Boston-Cambridge-Newton,
MA-NH 14460 | Boston-Worcester-Providence,
MA-RI-NH-CT 148 | Central | metro county (urban) | nonspecialized | https://maps.google.com/?q=NorfolkCounty+MA |
| | Plymouth County | MA | 25023 | Boston, MA 14454 | Boston-Cambridge-Newton,
MA-NH 14460 | Boston-Worcester-Providence,
MA-RI-NH-CT 148 | Central | metro county (urban) | nonspecialized | https://maps.google.com/?q=PlymouthCounty+MA |
| | Suffolk County | MA | 25025 | Boston, MA 14454 | Boston-Cambridge-Newton,
MA-NH 14460 | Boston-Worcester-Providence,
MA-RI-NH-CT 148 | Central | metro county (urban) | nonspecialized | https://maps.google.com/?q=SuffolkCounty+MA |