County outline
Where Thurston County is located
Area breakdown
Land accounts for 93.3% of Thurston County’s measured area and water for 6.7%. Its combined area converts to 2,004.9 square kilometers or approximately 495,418 acres.
Green: land · blue: water
| Measurement | Square miles | Square kilometers | Acres |
|---|---|---|---|
| Land | 722.513 | 1,871.3 | 462,408.3 |
| Water | 51.577 | 133.584 | 33,009.3 |
| Total | 774.09 | 2,004.884 | 495,417.6 |
How Thurston County compares
By original Census land area, Thurston County ranks #32 of 39 in Washington and #1235 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.
Its land area is 0.416 times the Washington county-equivalent median of 1,738.8 square miles. It accounts for 1.1% of the combined county land area in the state.
See the complete Washington ranking · What counts as a county equivalent?
Population and density of Thurston County
The Census Bureau estimates that 304,261 people lived in Thurston County on July 1, 2025. That ranks #244 of 3,222 county equivalents nationally and #6 of 39 in Washington. Since the April 1, 2020 estimates base of 294,790, the population has grown by 9,471 (+3.2%), compared with +3.8% for Washington as a whole.
With 722.5 square miles of land, that is 421 people per square mile (163 per km²), placing Thurston County #396 nationally for density and #5 in Washington. The median county equivalent has 47 people per square mile; the Washington median is 39. Put another way, there are about 1.5 acres of land per resident.
| July 1 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|---|
| Estimate | 296,013 | 298,313 | 298,556 | 299,197 | 302,132 | 304,261 |
| Change | — | +2,300 | +243 | +641 | +2,935 | +2,129 |
U.S. Census Bureau, Vintage 2025 population estimates. Estimates are revised each year and are not decennial census counts. Density divides the whole population by the whole county’s land area, so it describes an average, not how settlement is distributed within the county. Population sources and methods.
Cities and towns in Thurston County
7 incorporated places lie at least partly in Thurston County. Together they are home to 160,676 people (52.8%); the other 143,585 (47.2%) live outside any incorporated place, in unincorporated communities and rural areas.
The largest is Lacey city, with 58,833 residents in the county. The county seat, Olympia city, has 56,724 residents. Among places with at least 1,000 residents in 2020, Yelm city grew fastest since then (+13%).
| Incorporated place | Population 2025 | Since 2020 | Land mi² |
|---|---|---|---|
| Lacey city | 58,833 | +4.4% | 19.4 |
| Olympia cityCounty seat | 56,724 | +2.4% | 18.2 |
| Tumwater city | 28,010 | +7.6% | 17.7 |
| Yelm city | 12,043 | +13% | 5.813 |
| Rainier city | 2,495 | +5.5% | 1.738 |
| Tenino city | 1,941 | +3.7% | 1.456 |
| Bucoda town | 630 | +5.5% | 0.583 |
Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each place inside Thurston County. Land: 2026 Census Gazetteer, for the whole place even where it extends into other counties. How communities are listed.
Metropolitan area
Thurston County is a central county of the Olympia-Lacey-Tumwater, WA Metropolitan Statistical Area. Thurston County is the area’s only county equivalent, so the metro area has the same 722.5 square miles of land. By combined land it ranks #315 of 393 metropolitan areas, and #173 by population. It belongs to the Seattle-Tacoma, WA Combined Statistical Area.
ZIP codes
16 ZIP Code Tabulation Areas have land in Thurston County; 14 of them have most of their land inside the county, and the others mainly cover neighboring areas.
98501985029850398505985069851298513985169853098531985569856898576985799858998597
ZIP Code Tabulation Areas are the Census Bureau’s approximations of USPS ZIP Code service areas, from the 2020 Census relationship files. Lighter codes have less than half of their land in this county. Post-office-box and single-address ZIP Codes have no tabulation area.
Counties bordering Thurston County
Thurston County shares a land border with 4 county equivalents. Each of them has more land than Thurston County. The largest neighbor is Lewis County (2,402.8 mi²) and the smallest is Mason County (959.6 mi²). Together with its neighbors, Thurston County forms a block of 7,655.2 mi² of land, of which it holds 9.4%.
| Bordering county equivalent | Land mi² | Size vs. Thurston | Compare |
|---|---|---|---|
| Lewis County | 2,402.8 | 3.3× larger | Compare |
| Grays Harbor County | 1,902.3 | 2.6× larger | Compare |
| Pierce County | 1,668 | 2.3× larger | Compare |
| Mason County | 959.6 | 1.3× larger | Compare |
How big is Thurston County compared with U.S. states?
Thurston County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 1.4 times as much. Washington’s county land could hold about 92 areas the size of Thurston County.
Another way to picture it: the same land area would fill a square about 26.9 miles (43.3 km) on each side. Real county shapes are rarely square, so this is a scale reference rather than a width or driving distance.
State figures are the sums of each state’s county-equivalent land measurements in the same Census release, so states and counties are compared on the same basis. Published state totals can differ slightly because of rounding. Compare all states · Counties bigger than entire states.
What stands out about Thurston County?
Thurston County has more land than 1,987 of the other 3,221 county equivalents in the dataset.
A median is the middle county-equivalent measurement, not the average of the largest and smallest. All three bars use the same linear scale. Very small areas may appear as a thin sliver; the labels retain their values.
Does including water change its rank?
Using land plus water places Thurston County at #1,230 nationally by total area, 5 places closer to the top than its land rank. The water assigned to this geography moves it ahead of some county equivalents with more land.
Its water share is 6.7%, compared with a national county-equivalent median of 1.2% — 5.5 percentage points higher. This describes the statistical geography’s land/water mix, not flood exposure or developable land.
Closest positions in the national land ranking
These entries sit immediately beside Thurston County in the national ranking. They can be in different states and are not necessarily geographic neighbors.
| Land rank | County equivalent | Land mi² | Comparison |
|---|---|---|---|
| #1234 | Harrison County, Missouri | 722.5 | Compare |
| #1235 | Thurston County, Washington | 722.5 | This county |
| #1236 | Oliver County, North Dakota | 722.4 | Compare |
Calculated from the same Census release as the area table. Total-area order uses original ALAND + AWATER; water shares and chart labels use published square miles. Calculation details.
Representative coordinates
The Census internal point is 46.935822, -122.830152. It represents a location inside the geography; it is not necessarily the centroid or the address of a courthouse.
Source and precision
U.S. Census Bureau, 2026 Gazetteer Files, Counties. Original ALAND: 1,871,300,022 m²; AWATER: 133,584,568 m². Rankings use ALAND; exact ties use ascending GEOID. Tables preserve Census-published square miles to three decimals, with conversions based on those values.
Common questions
How big is Thurston County?
Thurston County, Washington has 722.5 square miles (1,871.3 km²) of land and 51.6 square miles of water, for a total area of 774.1 square miles. It ranks #1235 of 3,222 U.S. county equivalents by land area.
Is Thurston County the largest county in Washington?
No. Thurston County ranks #32 of 39 in Washington by land area. The largest is Okanogan County, with 5,266.2 square miles of land.
What counties border Thurston County?
Thurston County shares a land border with Lewis County, Pierce County, Grays Harbor County, and Mason County.
What is the population of Thurston County?
The Census Bureau estimates Thurston County had 304,261 residents on July 1, 2025, ranking #244 of 3,222 county equivalents. That is 421 people per square mile of land.
What is the county seat of Thurston County?
The county seat of Thurston County is Olympia.
What cities and towns are in Thurston County?
Thurston County has 7 incorporated places. The most populous five are Lacey city, Olympia city, Tumwater city, Yelm city, and Rainier city; 143,585 residents live outside any incorporated place.
Is Thurston County part of a metropolitan area?
Yes. It is a central county of the Olympia-Lacey-Tumwater, WA Metropolitan Statistical Area.
How many ZIP codes are in Thurston County?
16 ZIP Code Tabulation Areas have land in Thurston County, and 14 of them have most of their land inside the county. Census ZIP Code Tabulation Areas approximate USPS ZIP Code areas.
How does Thurston County compare with U.S. states?
It has less land than every state. Rhode Island, the smallest, has 1.4 times as much land.
How many acres of land are in Thurston County?
The land measurement converts to approximately 462,408 acres. Including water, total area is approximately 495,418 acres. One square mile equals 640 acres.
Why might another source show a different area?
Check whether it reports land or total area, its Census vintage, and its rounding. Our guide explains how to reconcile county area figures.
Can this establish a property boundary?
No. Statistical measurements and generalized maps do not establish property lines. Consult the relevant local surveying or land-records authority.