Delaware Counties by Population (2026)
by Kristen Carney
Updated: February 9, 2026
The most populous counties in Delaware are New Castle County with 577,961, Sussex County at 255,626, and Kent County with 187,604. You can get the most current Census population data for all 3 Delaware counties, sorted from the most populous counties in Delaware to the least, according to the 2024 American Community Survey.
Sure, you can copy this list right into your favorite spreadsheet tool. Or save yourself formatting headaches and grab the latest Delaware counties population data as a ready-to-use Excel™ file below. It's time to stop searching and start digging into data!
| Rank | County | Population |
|---|---|---|
| 1 | New Castle County | 577,961 |
| 2 | Sussex County | 255,626 |
| 3 | Kent County | 187,604 |
|
United States Census Bureau. B01001 SEX BY AGE, 2024 American Community Survey 5-Year Estimates. U.S. Census Bureau, American Community Survey Office. Web. January 29, 2026. http://www.census.gov/. |
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