Census ACS · 9 counties
Largest Counties in Connecticut
Connecticut has 9 counties with Census data available. The largest is Capitol Planning Region with a population of 969,029. County-level data is important because counties are the primary unit of local government in most states, responsible for courts, elections, public health, and infrastructure. Population distribution across counties reveals where growth is concentrated and where rural decline may be occurring.
Source: Census ACS 5-Year Estimates
| # | County | Population | Median Income |
|---|---|---|---|
| 1 | Western Connecticut Planning Region | 621,232 | $124,553 |
| 2 | Southeastern Connecticut Planning Region | 279,025 | $84,185 |
| 3 | South Central Connecticut Planning Region | 566,803 | $86,266 |
| 4 | Northwest Hills Planning Region | 112,848 | $91,035 |
| 5 | Northeastern Connecticut Planning Region | 95,829 | $87,564 |
| 6 | Naugatuck Valley Planning Region | 452,303 | $86,365 |
| 7 | Lower Connecticut River Valley Planning Region | 174,983 | $101,117 |
| 8 | Greater Bridgeport Planning Region | 326,296 | $87,135 |
| 9 | Capitol Planning Region | 969,029 | $91,541 |
More Rankings for Connecticut
Frequently Asked Questions
Capitol Planning Region is the #1 ranked county in Connecticut by population, with a value of 969,029 according to latest Census ACS data.
Connecticut has 9 counties tracked in latest Census ACS data.
All data comes from the American Community Survey (ACS) 5-Year estimates by the US Census Bureau.
Data from the American Community Survey 5-Year estimates. Covers all counties in Connecticut.
Source: U.S. Census Bureau ACS, 2026.