Wahkiakum County area

Wahkiakum County, Washington covers 286.7 square miles: 262.9 square miles of land and 23.8 square miles of water. Its county seat is Cathlamet. An estimated 4,873 people lived there in 2025.

Official Census measurements · GEOID 530692026 Gazetteer · retrieved September 27, 2026
Land area262.9 mi²
Water area23.8 mi²
Population (2025)4,873
People per mi²19

County outline

Generalized outline of Wahkiakum County, Washington
2025 Census cartographic boundary, fitted to this frame. County maps are not at a common scale. The 2026 area measurements below come from the separate Gazetteer release. Map source and limitations.

Where Wahkiakum County is located

Wahkiakum County highlighted on a map of all U.S. county equivalents. About the maps

Area breakdown

Land accounts for 91.7% of Wahkiakum County’s measured area and water for 8.3%. Its combined area converts to 742.5 square kilometers or approximately 183,487 acres.

Green: land · blue: water

MeasurementSquare milesSquare kilometersAcres
Land262.928680.98168,273.9
Water23.7761.56415,212.8
Total286.698742.544183,486.7

How Wahkiakum County compares

By original Census land area, Wahkiakum County ranks #37 of 39 in Washington and #2880 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.

Its land area is 0.151 times the Washington county-equivalent median of 1,738.8 square miles. It accounts for 0.4% of the combined county land area in the state.

See the complete Washington ranking · What counts as a county equivalent?

Population and density of Wahkiakum County

The Census Bureau estimates that 4,873 people lived in Wahkiakum County on July 1, 2025. That ranks #2,900 of 3,222 county equivalents nationally and #37 of 39 in Washington. Since the April 1, 2020 estimates base of 4,420, the population has grown by 453 (+10.2%), compared with +3.8% for Washington as a whole.

With 262.9 square miles of land, that is 19 people per square mile (7.2 per km²), placing Wahkiakum County #2,367 nationally for density and #30 in Washington. The median county equivalent has 47 people per square mile; the Washington median is 39. Put another way, there are about 35 acres of land per resident.

Estimated population, 2020–2025 · line scaled to this county’s own range
July 1202020212022202320242025
Estimate4,4464,5874,6934,7644,8134,873
Change—+141+106+71+49+60

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 Wahkiakum County

1 incorporated place lies at least partly in Wahkiakum County. Together they are home to 610 people (12.5%); the other 4,263 (87.5%) live outside any incorporated place, in unincorporated communities and rural areas.

The largest is Cathlamet town, with 610 residents in the county.

Metropolitan area

Wahkiakum County is not part of any metropolitan or micropolitan statistical area in the Office of Management and Budget’s July 2023 delineation; 1,306 other county equivalents are also outside one. These areas are built around an urban core of at least 10,000 people plus the counties tied to it by commuting, so counties outside them are generally rural.

ZIP codes

6 ZIP Code Tabulation Areas have land in Wahkiakum County; 3 of them have most of their land inside the county, and the others mainly cover neighboring areas.

986129862198632986389864398647

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 Wahkiakum County

Wahkiakum County shares a land border with 5 county equivalents, including 2 in Oregon. Each of them has more land than Wahkiakum County. The largest neighbor is Lewis County (2,402.8 mi²) and the smallest is Columbia County (658.7 mi²). Together with its neighbors, Wahkiakum County forms a block of 6,227.2 mi² of land, of which it holds 4.2%.

Map of Wahkiakum County and the 5 county equivalents that border it Pacific County, Washington: 933.4 mi² landCowlitz County, Washington: 1,141.2 mi² landClatsop County, Oregon: 828.2 mi² landColumbia County, Oregon: 658.7 mi² landLewis County, Washington: 2,402.8 mi² land
Wahkiakum County (dark) and its bordering county equivalents. Select a neighbor to open its profile. Drawn from the 2025 Census cartographic boundaries in an equal-area projection. How borders are determined.
Bordering county equivalentLand mi²Size vs. WahkiakumCompare
Lewis County2,402.89.1× largerCompare
Cowlitz County1,141.24.3× largerCompare
Pacific County933.43.5× largerCompare
Clatsop CountyOregon828.23.2× largerCompare
Columbia CountyOregon658.72.5× largerCompare

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

Wahkiakum County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 3.9 times as much. Washington’s county land could hold about 253 areas the size of Wahkiakum County.

Land area: Wahkiakum County and the closest-sized states
Wahkiakum County262.9 mi²
Rhode Island1,033.9 mi²

Another way to picture it: the same land area would fill a square about 16.2 miles (26.1 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 Wahkiakum County?

Wahkiakum County has more land than 342 of the other 3,221 county equivalents in the dataset.

Land area compared with the typical county equivalent
Wahkiakum County262.9 mi²
Washington median1,738.8 mi²
National median604.5 mi²

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 Wahkiakum County at #2,868 nationally by total area, 12 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 8.3%, compared with a national county-equivalent median of 1.2% — 7.1 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 Wahkiakum County in the national ranking. They can be in different states and are not necessarily geographic neighbors.

Land rankCounty equivalentLand mi²Comparison
#2879Davie County, North Carolina263.7Compare
#2880Wahkiakum County, Washington262.9This county
#2881Johnson County, Kentucky262Compare

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 46.314477, -123.402186. 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: 680,980,757 m²; AWATER: 61,564,427 m². Rankings use ALAND; exact ties use ascending GEOID. Tables preserve Census-published square miles to three decimals, with conversions based on those values.

Download the official county source ZIP ↗ · Methodology

Common questions

How big is Wahkiakum County?

Wahkiakum County, Washington has 262.9 square miles (681 km²) of land and 23.8 square miles of water, for a total area of 286.7 square miles. It ranks #2880 of 3,222 U.S. county equivalents by land area.

Is Wahkiakum County the largest county in Washington?

No. Wahkiakum County ranks #37 of 39 in Washington by land area. The largest is Okanogan County, with 5,266.2 square miles of land.

What counties border Wahkiakum County?

Wahkiakum County shares a land border with Pacific County, Cowlitz County, Clatsop County, Oregon, Columbia County, Oregon, and Lewis County.

What is the population of Wahkiakum County?

The Census Bureau estimates Wahkiakum County had 4,873 residents on July 1, 2025, ranking #2,900 of 3,222 county equivalents. That is 19 people per square mile of land.

What is the county seat of Wahkiakum County?

The county seat of Wahkiakum County is Cathlamet.

Is Wahkiakum County part of a metropolitan area?

No. Wahkiakum County is outside every metropolitan and micropolitan statistical area in the July 2023 OMB delineation.

How many ZIP codes are in Wahkiakum County?

6 ZIP Code Tabulation Areas have land in Wahkiakum County, and 3 of them have most of their land inside the county. Census ZIP Code Tabulation Areas approximate USPS ZIP Code areas.

How does Wahkiakum County compare with U.S. states?

It has less land than every state. Rhode Island, the smallest, has 3.9 times as much land.

How many acres of land are in Wahkiakum County?

The land measurement converts to approximately 168,274 acres. Including water, total area is approximately 183,487 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.

Cite this county

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