Southeastern Connecticut Planning Region area

Population and density of Southeastern Connecticut Planning Region

The Census Bureau estimates that 284,015 people lived in Southeastern Connecticut Planning Region on July 1, 2025. That ranks #257 of 3,222 county equivalents nationally and #6 of 9 in Connecticut. Since the April 1, 2020 estimates base of 280,467, the population has grown by 3,548 (+1.3%), compared with +2.2% for Connecticut as a whole.

With 598.1 square miles of land, that is 475 people per square mile (183 per km²), placing Southeastern Connecticut Planning Region #352 nationally for density and #6 in Connecticut. The median county equivalent has 47 people per square mile; the Connecticut median is 968. Put another way, there are about 1.3 acres of land per resident.

U.S. Census Bureau, Vintage 2025 population estimates. Estimates are revised each year and are not decennial census counts. Density divides the whole population by the whole county’s land area, so it describes an average, not how settlement is distributed within the county. Population sources and methods.

Cities and towns in Southeastern Connecticut Planning Region

Southeastern Connecticut Planning Region is divided into 19 cities and towns. In Connecticut, county subdivisions are local governments, and together they cover all of the county’s land and residents.

The most populous is Norwich town, with 40,001 residents (14.1% of the county). The largest by land is North Stonington town, at 54.2 mi², or 9.1% of the county’s land. Among those with at least 1,000 residents in 2020, Waterford town grew fastest since then (+4.4%).

Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each subdivision inside Southeastern Connecticut Planning Region. Land: 2026 Census Gazetteer. How communities are listed.

Metropolitan area

Southeastern Connecticut Planning Region is a central county of the Norwich-New London-Willimantic, CT Metropolitan Statistical Area. Southeastern Connecticut Planning Region is the area’s only county equivalent, so the metro area has the same 598.1 square miles of land. By combined land it ranks #340 of 393 metropolitan areas, and #178 by population. It belongs to the New Haven-Hartford-Waterbury, CT Combined Statistical Area.

ZIP codes

34 ZIP Code Tabulation Areas have land in Southeastern Connecticut Planning Region; 33 of them have most of their land inside the county, and the others mainly cover neighboring areas.

06226062490625406256062660628006320063300633106333063340633506336063380633906340063500635106353063550635706359063600636506370063750637806379063800638206385063890641506420

ZIP Code Tabulation Areas are the Census Bureau’s approximations of USPS ZIP Code service areas, from the 2020 Census relationship files. Lighter codes have less than half of their land in this county. Post-office-box and single-address ZIP Codes have no tabulation area. Connecticut areas are assigned through their towns, because planning regions replaced the state’s counties after 2020.

Counties bordering Southeastern Connecticut Planning Region

Southeastern Connecticut Planning Region shares a land border with 4 county equivalents, including 1 in Rhode Island. It has more land than 3 of them. The largest neighbor is Capitol Planning Region (1,027.4 mi²) and the smallest is Washington County (329.3 mi²). Together with its neighbors, Southeastern Connecticut Planning Region forms a block of 2,932.8 mi² of land, of which it holds 20.4%.

How big is Southeastern Connecticut Planning Region compared with U.S. states?

Southeastern Connecticut Planning Region has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 1.7 times as much. Connecticut’s county land could hold about 8.1 areas the size of Southeastern Connecticut Planning Region.

Another way to picture it: the same land area would fill a square about 24.5 miles (39.4 km) on each side. Real county shapes are rarely square, so this is a scale reference rather than a width or driving distance.

State figures are the sums of each state’s county-equivalent land measurements in the same Census release, so states and counties are compared on the same basis. Published state totals can differ slightly because of rounding. Compare all states · Counties bigger than entire states.

What stands out about Southeastern Connecticut Planning Region?

Southeastern Connecticut Planning Region has more land than 1,592 of the other 3,221 county equivalents in the dataset.

A median is the middle county-equivalent measurement, not the average of the largest and smallest. All three bars use the same linear scale. Very small areas may appear as a thin sliver; the labels retain their values.

Does including water change its rank?

Using land plus water places Southeastern Connecticut Planning Region at #1,488 nationally by total area, 142 places closer to the top than its land rank. The water assigned to this geography moves it ahead of some county equivalents with more land.

Its water share is 12.3%, compared with a national county-equivalent median of 1.2% — 11.1 percentage points higher. This describes the statistical geography’s land/water mix, not flood exposure or developable land.

Closest positions in the national land ranking

These entries sit immediately beside Southeastern Connecticut Planning Region in the national ranking. They can be in different states and are not necessarily geographic neighbors.

Calculated from the same Census release as the area table. Total-area order uses original ALAND + AWATER; water shares and chart labels use published square miles. Calculation details.