County research and study

Delaware county reference

3 counties and county equivalents in Delaware. Search names or FIPS codes, compare Census geography and keep the original sources with your work.

Kent County
Delaware · FIPS 10001
194,786 residents · 2025 estimate
New Castle County
Delaware · FIPS 10003
588,026 residents · 2025 estimate
Sussex County
Delaware · FIPS 10005
277,140 residents · 2025 estimate

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Use a county profile as a source-reading exercise or the geographic context for your own research. Keep the county FIPS identifier with your notes so that similarly named places in different states are not mixed.

The figures describe the county; they are not an evaluation of schools or an estimate of educational outcomes.

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Geography: 2025 U.S. Census Gazetteer. Population: Vintage 2025 estimates, July 1, 2025. County equivalents include parishes, boroughs, independent cities and planning regions. Puerto Rico population is not supplied by this population file.