Census Bureau July 1, 2025 estimates put Delaware at 1,059,952 residents. New Castle County had 588,026, Kent County 194,786 and Sussex County 277,140. From the 2020 estimate base to 2025, Sussex County grew 16.8%, compared with 7.1% statewide and 3.0% in New Castle County. These are population estimates, not headcounts from a new decennial census. County agricultural output is not inferred from population.
What to keep in view
- Delaware: 1,059,952 residents
- New Castle: 588,026; Kent: 194,786; Sussex: 277,140
- 2020 estimate base to 2025: Sussex +16.8%; Delaware +7.1%; New Castle +3.0%
We distinguish a source’s reported observation from our interpretation. Where an update is preliminary, approximate or not comparable across geographies, we say so. This page is an explanatory guide, not an official government notice or professional advice.
Go to the original records
State population and demographic estimates.
New Castle County estimate.
Kent County estimate.
Sussex County estimate.