COUNTY · PA
Delaware County, Pennsylvania
Delaware County is a county in Pennsylvania with FIPS code 42045 and an estimated population of 576,720 (Census 2023), 5th largest of 67 in the state.
County facts
- Name
- Delaware County
- State
- Pennsylvania
- Type
- county
- FIPS code
- 42045
- State FIPS
- 42
- Population (2023)
- 576,720
- Change since 2020
- +0.1%
- State rank
- 5 of 67
Population is the Census Bureau’s Vintage 2023 estimate.
Questions
What is the FIPS code for Delaware County?
Delaware County, Pennsylvania has the five-digit FIPS code 42045: 42 for the state and 045 for the county.
What state is Delaware County in?
Delaware County is in Pennsylvania.
How do I know if an address is in this county?
Use the address lookup. ZIP codes and city names can cross county lines, so an address is the reliable check.
Sources: U.S. Census Bureau geographic reference files; Census Bureau Population Estimates, Vintage 2023. Last reviewed 2026-10-27.