Connecticut’s Population Continued to Grow from 2024 to 2025, Despite Decreased Net International Migration and High Domestic Out-Migration from Western CT
In March, the Census Bureau released its Vintage 2025 County Population Estimates – which, in Connecticut, are for our nine “county-equivalent” planning regions. The data include annual total population estimates for states and counties or county-equivalents for July 1, 2020, to July 1, 2025, as well as estimated “components of change” – births, deaths, and migration – between each year.
Read on to learn about how Connecticut’s population has changed, overall and by planning region.
To explore Connecticut’s population estimates and housing unit permits over time and by town, check out our updated CT Population Estimates Dashboard.
Connecticut’s total population increased from 2024 to 2025, but at a slower rate than over the two prior years
According to the Vintage 2025 population estimates, Connecticut’s total population as of July 1, 2025, was 3,688,496 – a slight increase of 14,047 residents (+0.38%) from July 1, 2024.
This continues a consistent upward trend in Connecticut’s population since 2021, although it represents a decrease in the estimated rate of growth compared to that seen in 2024 (+0.91%) and 2023 (+0.63%). This decrease in the rate of growth mirrors a national trend of slowing or reversing population growth between July 1, 2024, and July 1, 2025.
Connecticut’s population increase in each year since 2021 has been driven primarily by net positive international migration
The Census Bureau estimates total population change by adding “components of change” to the population count as of the last decennial census (April 1, 2020). These components of change include natural change (births minus deaths), net domestic migration (including household migration and group quarters change), and net international migration. The charts below show the components of change across each time point in the Vintage 2025 estimates series.
Between July 2024 and 2025, the Census Bureau estimates that Connecticut experienced a net gain of about 17,500 international migrants. In this same year, Connecticut experienced a net loss of about 6,000 household residents due to domestic migration, a net gain of about 650 group quarters residents (e.g., students living in college dormitories), and a net gain of about 2,300 residents due to natural change (births minus deaths).
However, Connecticut’s net international migration in 2024-2025 was less than half of that seen in the prior year and was the lowest recorded number since 2020-2021, when international migration was restricted due to the COVID-19 pandemic. This is consistent with a nationwide decline in net international migration in 2024-2025, coinciding with federal immigration policy changes implemented in the first six months of the Trump administration.
Notably, the Census Bureau’s analysis of administrative data on immigration reveals a steep decrease specifically in humanitarian immigrants to the United States in July 2024-2025, while other categories of foreign-born immigration remained relatively stable. The Census Bureau also noted an increase in the number of U.S. residents leaving the United States in 2024-2025.
The greatest population growth was seen in the Capitol and Western Connecticut Planning Regions
All planning regions showed either population stability or growth from July 2024 to July 2025. The largest absolute population growth was seen in the Capitol (+4,921) and Western Connecticut (+2,761) Planning Regions, followed by Naugatuck Valley (+1,869).
Net positive international migration drove population growth in most planning regions, despite substantial domestic out-migration from Western Connecticut
Within each planning region that showed substantial population growth, this growth was due primarily to net positive international migration. The greatest net international migration was seen in the Capitol (+4,741) and Western Connecticut (+4,753) Planning Regions, followed by the South Central Connecticut (+2,736) and Greater Bridgeport (+2,361) Planning Regions.
However, much of this net positive international migration was counterbalanced by net negative domestic household migration in the Western Connecticut (-3,773), South Central Connecticut (-1,704), and Greater Bridgeport (-2,057) Planning Regions. Indeed, the domestic migration estimates suggest a substantial domestic outflow of residents specifically from southwestern Connecticut.
Most planning regions experienced relatively little natural population change (births minus deaths) between July 2024 and July 2025, with the exception of the Western Connecticut Planning Region, where there were 1,648 more births than deaths, and the Greater Bridgeport Planning Region, where there were 974 more births than deaths.
Notes
For the Vintage 2025 estimates, the Census Bureau modified their methodology for estimating net international migration. As we discussed in a prior blog post, the previous year’s (Vintage 2024) net international migration estimates for 2022 through 2024 had been adjusted upwards using administrative data on the increase in humanitarian migration into the United States since 2021, but the distribution of these migrants to specific states and counties was not based on data on where these migrants settled. In Vintage 2025, the Census Bureau improved on their methodology for distributing the national humanitarian migrant totals to states and counties using data from the Department of Justice’s Executive Office of Immigration Review (EOIR) on where these migrants were living. This change only impacted the estimates for 2022 through 2024. Due to the drop in humanitarian immigration into the U.S. in 2025, the estimates for 2025 (derived from the American Community Survey) did not need to be adjusted using administrative data.
Our analysis shows that methodological changes to the net international migration estimates for 2022 through 2024 resulted in small decreases in Connecticut’s estimated net international migration in these years compared to Vintage 2024 (a 2% decrease for 2021-2022, an 8% decrease for 2022-2023, and a 2% decrease for 2023-2024). However, this yielded a negligible change in Connecticut’s total population estimates for those years (-0.05% to +0.02%).
For more information about this and other methodological changes for the Vintage 2025 estimates, see the Census Bureau’s Vintage 2025 Release Notes and their Random Samplings blog post on changes to the net international migration estimates methodology.
For full details about how the Census Bureau develops their population estimates, see the Census Bureau’s Vintage 2025 Methodology Statement and their Population Estimates Program webpage.
For More Information
To explore Connecticut’s population estimates and housing unit permits over time and by town, check out our updated CT Population Estimates Dashboard. To learn more about Census Bureau data and resources provided by CTData, head to our Census Data Portal. Explore other data sets and analysis at our data by topic and data projects pages.
You can stay up-to-date on the latest data and tools by subscribing to our newsletter and following CTData on Facebook, LinkedIn, Instagram, and Bluesky.