Suffolk County, Massachusetts Map with Towns and Population
| County | Population | Land area | Polygon area | Difference | Density | Share of county |
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Boundaries and land area: United States Census Bureau, TIGERweb, public domain. Population: 2020 Census of Population and Housing. Aerial imagery: United States Geological Survey, The National Map, public domain.
How to use this map
This is Suffolk County, drawn as the 4 cities and towns it is divided into. Pick a map type along the top: Cities and towns colours them so no two neighbours share a fill, Density shades them by people per square kilometre, Satellite swaps the flat colours for aerial imagery, and Blank outline gives you black on white for printing. Click any town, or any row in the table, for its population, land area and density.
Switch between metric and imperial with the Units control. Everything on the page follows it, including the downloads.
What this county is made of
Suffolk County held 797,936 people at the 2020 Census across 151 square kilometres of land, which works out at 5288.2 people per square kilometre. Its seat is Boston. Within Massachusetts it is fourth by population out of 14 and thirteenth by land area, holding 11.4 percent of the state.
The 4 cities and towns on this map are the units the county is actually administered through, and they cover every square metre of it. Boston is the largest at 675,647 people, and Winthrop Town the smallest at 19,316.
The cities and towns add up to exactly 797,936, the published county figure, which is how the numbers on this page are checked.
Where the data comes from
Boundaries and land areas come from the United States Census Bureau through the TIGERweb service. County populations are 2020 Census counts. The county seat comes from the published county list for Massachusetts.
Aerial imagery, and how it is fitted to the map
The Satellite map type replaces the flat colours with real aerial imagery from the United States Geological Survey, taken from The National Map. Most of it comes from the National Agriculture Imagery Program, flown at one metre resolution or better.
That resolution matters at this scale. The national and state maps on this site use a NASA composite at five hundred metres per pixel, which is right for a whole country but turns to mush over a single county. At one metre you can pick out reservoirs, the road network, the line where development gives way to woodland, and the shape of built up areas within each town.
The imagery arrives as a plain latitude and longitude grid while this map is drawn in Lambert conformal conic, so every pixel is converted back to a latitude and longitude and the matching pixel is read from the source. Both then sit in the same projection, which is why the boundaries follow the ground instead of drifting away from it.
The imagery is public domain, as work of the United States government. The credit is drawn onto the map itself so it travels with the image when you download it.
A check you can repeat on paper
Take Boston, the largest town here.
The published figures give it 675,647 people and 125.2 square kilometres of land. Divide one by the other and you get 5396.5 people per square kilometre.
Select it on the map and the Selection panel reads the same figure. Add the 4 land areas in the table and they come to 151 square kilometres, the published land area of Suffolk County.
Mistakes that catch people out
Treating the drawn area as land. The county outline includes its inland water, and here the boundary encloses about 89 percent more area than the land figure. Density on this page is always computed on land.
Confusing the county with the place that shares its name. Boston is the seat of Suffolk County, not the whole of it, and the county contains 3 other cities and towns besides.
Mixing census years. Every population here is 2020. Figures from a later estimate will not reconcile against anything on this page.
Related Calculators and Reference
- Massachusetts County Map: all 14 counties of Massachusetts with population, land area and density.
- United States Map: all fifty states, with a county map behind each one.
- United States Census Bureau, Geography: the source of the boundaries and land areas used here.
- The National Map viewer: the USGS browser behind the aerial imagery on this page.
Boundaries and land area: United States Census Bureau, TIGERweb, public domain. Population: 2020 Census of Population and Housing. Aerial imagery: United States Geological Survey, The National Map, public domain.