COUNTY · WA
Mason County, Washington
Mason County is a county in Washington with FIPS code 53045 and an estimated population of 68,389 (Census 2023), 20th largest of 39 in the state.
County facts
- Name
- Mason County
- State
- Washington
- Type
- county
- FIPS code
- 53045
- State FIPS
- 53
- Population (2023)
- 68,389
- Change since 2020
- +3.6%
- State rank
- 20 of 39
Population is the Census Bureau’s Vintage 2023 estimate.
Questions
What is the FIPS code for Mason County?
Mason County, Washington has the five-digit FIPS code 53045: 53 for the state and 045 for the county.
What state is Mason County in?
Mason County is in Washington.
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.