Mason County area

Population and density of Mason County

The Census Bureau estimates that 71,165 people lived in Mason County on July 1, 2025. That ranks #788 of 3,222 county equivalents nationally and #20 of 39 in Washington. Since the April 1, 2020 estimates base of 65,721, the population has grown by 5,444 (+8.3%), compared with +3.8% for Washington as a whole.

With 959.6 square miles of land, that is 74 people per square mile (29 per km²), placing Mason County #1,217 nationally for density and #15 in Washington. The median county equivalent has 47 people per square mile; the Washington median is 39. Put another way, there are about 8.6 acres of land per resident.

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 Mason County

1 incorporated place lies at least partly in Mason County. Together they are home to 10,921 people (15.3%); the other 60,244 (84.7%) live outside any incorporated place, in unincorporated communities and rural areas.

The largest is Shelton city, with 10,921 residents in the county.

Metropolitan area

Mason County is a central county of the Shelton, WA Micropolitan Statistical Area. Mason County is the area’s only county equivalent, so the micro area has the same 959.6 square miles of land. By combined land it ranks #192 of 542 micropolitan areas, and #104 by population. It belongs to the Seattle-Tacoma, WA Combined Statistical Area.

ZIP codes

15 ZIP Code Tabulation Areas have land in Mason County; 9 of them have most of their land inside the county, and the others mainly cover neighboring areas.

983129838098502985249852898541985469854898555985579856098563985849858898592

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 Mason County

Mason County shares a land border with 5 county equivalents. It has more land than 2 of them. The largest neighbor is Grays Harbor County (1,902.3 mi²) and the smallest is Kitsap County (395.1 mi²). Together with its neighbors, Mason County forms a block of 7,451.2 mi² of land, of which it holds 12.9%.

How big is Mason County compared with U.S. states?

Mason County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 1.1 times as much. Washington’s county land could hold about 69 areas the size of Mason County.

Another way to picture it: the same land area would fill a square about 31 miles (49.9 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 Mason County?

Mason County has more land than 2,491 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 Mason County at #720 nationally by total area, 11 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 8.7%, compared with a national county-equivalent median of 1.2% — 7.5 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 Mason County in the national ranking. They can be in different states and are not necessarily geographic neighbors.

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.