Cowlitz County area

Population and density of Cowlitz County

The Census Bureau estimates that 114,885 people lived in Cowlitz County on July 1, 2025. That ranks #565 of 3,222 county equivalents nationally and #12 of 39 in Washington. Since the April 1, 2020 estimates base of 110,728, the population has grown by 4,157 (+3.8%), compared with +3.8% for Washington as a whole.

With 1,141.2 square miles of land, that is 101 people per square mile (39 per km²), placing Cowlitz County #991 nationally for density and #12 in Washington. The median county equivalent has 47 people per square mile; the Washington median is 39. Put another way, there are about 6.4 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 Cowlitz County

5 incorporated places lie at least partly in Cowlitz County. Together they are home to 63,301 people (55.1%); the other 51,584 (44.9%) live outside any incorporated place, in unincorporated communities and rural areas.

The largest is Longview city, with 38,362 residents in the county. The county seat, Kelso city, has 12,801 residents. Among places with at least 1,000 residents in 2020, Kalama city grew fastest since then (+6.9%).

Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each place inside Cowlitz County. Land: 2026 Census Gazetteer, for the whole place even where it extends into other counties. How communities are listed.

Metropolitan area

Cowlitz County is a central county of the Longview-Kelso, WA Metropolitan Statistical Area. Cowlitz County is the area’s only county equivalent, so the metro area has the same 1,141.2 square miles of land. By combined land it ranks #265 of 393 metropolitan areas, and #344 by population. It belongs to the Portland-Vancouver-Salem, OR-WA Combined Statistical Area.

ZIP codes

12 ZIP Code Tabulation Areas have land in Cowlitz County; 10 of them have most of their land inside the county, and the others mainly cover neighboring areas.

985819860198603986099861198616986259862698632986459864998674

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 Cowlitz County

Cowlitz County shares a land border with 5 county equivalents, including 1 in Oregon. It has more land than 3 of them. The largest neighbor is Lewis County (2,402.8 mi²) and the smallest is Wahkiakum County (262.9 mi²). Together with its neighbors, Cowlitz County forms a block of 6,752.4 mi² of land, of which it holds 16.9%.

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

Cowlitz County has more land than 1 of the 50 states. It is about 1.1 times the land area of Rhode Island (1,033.9 mi²), while Delaware, the next larger state, has 1.7 times as much land (1,948.6 mi²). Washington’s county land could hold about 58 areas the size of Cowlitz County.

Another way to picture it: the same land area would fill a square about 33.8 miles (54.4 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 Cowlitz County?

Cowlitz County has more land than 2,678 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 Cowlitz County at #609 nationally by total area, 65 places farther from the top than its land rank. Other county equivalents gain more area when their water measurements are included.

Its water share is 2.2%, compared with a national county-equivalent median of 1.2% — 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 Cowlitz 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.