County facts · Land area · October 22, 2026

Largest Counties in Massachusetts by Area and Population

The largest Massachusetts counties by land area and by 2023 population, plus the smallest, county seats and a link to each official parcel map.

Looking for the largest counties in Massachusetts? Massachusetts has 14 counties covering about 7,801 square miles of land, based on the Census Bureau's 2020 Gazetteer. The largest by land area is Worcester County, at about 1,511 square miles, roughly 33 times the size of the smallest, Nantucket County (46 sq mi). Measured by people instead, the largest is Middlesex County, with about 1,623,952 residents in the Census Bureau's July 1, 2023 estimate.

Each table below links the county's Platbookmapper page and its official parcel viewer, so you can go straight from the numbers to the property lines.

Massachusetts counties at a glance

• Counties: 14
• Land area: about 7,801 sq mi, plus about 2,753 sq mi of water inside county lines
• Residents, 2023 estimates: about 7,001,399, or about 898 people per square mile of land
• Median county land area: about 540 sq mi
• With a verified public parcel viewer in our directory: 14 of 14 (14 of them through a statewide viewer)

Every county in Massachusetts points to the same statewide viewer in our directory, the MassGIS Interactive Property Map, so one search box covers the whole state and the parcel pop-ups look the same on both sides of a county line.

The 10 largest Massachusetts counties by land area

Together these 10 cover about 92% of Massachusetts's land area and hold about 85% of its residents.

The 10 most populous Massachusetts counties

These 10 hold about 97% of Massachusetts's residents in the 2023 estimates.

The smallest Massachusetts counties

With only 14 counties, the bottom of the list is short. The three smallest by land area are Nantucket County (about 46 sq mi, 14,444 residents), Suffolk County (about 58 sq mi, 768,425 residents) and Dukes County (about 103 sq mi, 20,819 residents).

Most and least crowded

• Most people per square mile: Suffolk County, about 13,191 (then Middlesex County, 1,986, and Norfolk County, 1,837)
• Fewest people per square mile: Franklin County, about 101 (then Berkshire County, 137, and Dukes County, 202)

Counties with the most water

The Census Bureau reports water separately from land. It counts lakes, reservoirs, rivers and, along a coast or a Great Lake, the water inside the boundary.

• Barnstable County: about 911 sq mi of water, 70% of its total area
• Plymouth County: about 435 sq mi of water, 40% of its total area
• Dukes County: about 388 sq mi of water, 79% of its total area

Using these numbers in a land search

• Land area is not parcel count. A large rural county can hold fewer parcels than a small suburban one, so size alone says little about how busy its parcel map is.
• Search, don't scroll. In a big county, type an address, owner name or parcel number into the viewer's search box, where it has one, instead of panning across the map.
• Records follow the county line. Deeds, plats and tax bills are kept by the county where the parcel sits, so a tract that crosses a county line usually has a parcel number on each side.
• Rounded figures. Land and water areas are rounded to whole square miles (one decimal for very small places). People per square mile is the 2023 estimate divided by land area.

Related guides

• Massachusetts landowner maps for hunting
• Largest county in each state
• Largest counties in the US by land area

More: All Massachusetts counties on Platbookmapper

Sources

• U.S. Census Bureau Gazetteer files, 2020 county land and water area.
• U.S. Census Bureau, Population Estimates Program, county totals, Vintage 2023 (July 1, 2023 estimates)
• Platbookmapper county GIS directory (live data file behind our county pages, pulled October 22, 2026) for each official parcel viewer.
• County seats: Wikidata (county seat property), cross-checked against Census place names.