COUNTY · TX
Williamson County, Texas
Williamson County is a county in Texas with FIPS code 48491 and an estimated population of 697,191 (Census 2023), 12th largest of 254 in the state.
County facts
- Name
- Williamson County
- State
- Texas
- Type
- county
- FIPS code
- 48491
- State FIPS
- 48
- Population (2023)
- 697,191
- Change since 2020
- +13.3%
- State rank
- 12 of 254
Population is the Census Bureau’s Vintage 2023 estimate.
Questions
What is the FIPS code for Williamson County?
Williamson County, Texas has the five-digit FIPS code 48491: 48 for the state and 491 for the county.
What state is Williamson County in?
Williamson County is in Texas.
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.