Prior to the Europeans' arrival to the area, it was inhabited by numerous Native American tribes, with the Cowlitz tribe being the largest. They were drawn to the region by the abundance ofsalmon. The Cowlitz are considered to be the first regional inhabitants to engage in commerce as they traded extensively with other tribes inWestern andEastern Washington. The Cowlitz Indian population declined significantly from the 1829-1830smallpox outbreak.
European explorers discovered and began navigating theColumbia River in 1792 asBritish Lieutenant W. R. Broughton sailed up the river to and past present day Cowlitz County. Then on November 5, 1805,Lewis and Clark camped at the mouth of theKalama River. Over the following days, they would reach the present sites of Kelso and Longview.
By the 1820s, theHudson's Bay Company had established a lucrativefur trade in the region. Furs were shipped down theCowlitz River to the Columbia where they were loaded and shipped around the world. Trade declined significantly in the late 1830s as over-hunting reduced the annual yields, and wearing fur had become less fashionable.
During the next several decades, white settlement of the region was in full swing. Most of the settlers homesteaded near the tributaries that fed the Columbia River, forming settlements. The first was Monticello, near present-day Longview. In 1841 several families with the HBC directedSinclair expedition fromRed River Colony settled there.
On November 25, 1852, at Monticello, settlers from the Cowlitz andPuget Sound regions drafted a petition (theMonticello Convention) to the federal government, calling for a separate territory north of the Columbia River to be carved out of the existingOregon Territory. The petition was successful; three months later theUnited States Congress formed the Columbia Territory, although it was soon renamedWashington Territory.
The newly separated territory was governed by two existing counties. In August 1845, the Oregon Territorial government had created Vancouver County. Its boundary covered the entire area of present-day Washington state. In December of that same year, the Oregon Territorial government sliced off the eastern portion to createLewis County. In 1849 the reduced Vancouver County was renamedClark County. So when the new Washington Territorial government began functioning, among its first actions was the creation of Cowlitz County, from the southwestern portion of Clark County. This proclamation was finalized on April 24, 1854, signed into law by GovernorIsaac Stevens. Later in 1854, the western portion of the new county was partitioned off to formWahkiakum County; otherwise the county's boundary has remained unchanged until the present.
Nearly every town that sprang up in the late 19th century began around alogging orlumber-milling operation. In the latter half of the 1920s, theWeyerhaeuser Company andLong-Bell Lumber Company established processing facilities. At the time, these two facilities were the first and second largest in the world. The county is still heavily dependent on the timber industry.[5]
Four towns have functioned as the Cowlitz County seat:[6]
Cowlitz County is in the southwestern part of Washington state. According to theU.S. Census Bureau, the county has a total area of 1,166 square miles (3,020 km2), of which 1,140 square miles (3,000 km2) is land and 26 square miles (67 km2) (2.2%) is water.[7]
Cowlitz County is part of the Puget Sound – Willamette Depression, a geologic formation extending southward from the Puget Sound to theWillamette Valley inOregon. Nestled against theCascade Mountains, many of the county's major rivers originate in this range, including the Columbia, Cowlitz,Coweeman, Kalama,Lewis andToutle.[5]
Cowlitz County is one of the state's smaller counties (28 of 39).[8]
As of the2020 census, there were 110,730 people, 42,787 households, and 28,644 families residing in the county.[15] Thepopulation density was 97.0 inhabitants per square mile (37.5/km2). There were 45,424 housing units at an average density of 39.8 inhabitants per square mile (15.4/km2).
22.7% of residents were under the age of 18, 5.6% were under 5 years of age, and 19.8% were 65 years of age or older; the median age was 41.0 years. For every 100 females there were 98.1 males, and for every 100 females age 18 and over there were 96.6 males.[16] 67.0% of residents lived in urban areas and 33.0% lived in rural areas.[17]
Cowlitz County, Washington – Racial and ethnic composition Note: the US Census treats Hispanic/Latino as an ethnic category. This table excludes Latinos from the racial categories and assigns them to a separate category. Hispanics/Latinos may be of any race.
There were 42,787 households in the county, of which 29.8% had children under the age of 18 living with them and 24.4% had a female householder with no spouse or partner present. About 25.6% of all households were made up of individuals and 12.5% had someone living alone who was 65 years of age or older.[16]
Of those 45,424 housing units, 5.8% were vacant. Among occupied housing units, 67.7% were owner-occupied and 32.3% were renter-occupied. The homeowner vacancy rate was 1.2% and the rental vacancy rate was 5.5%.[16]
As of the2010 census, there were 102,410 people, 40,244 households, and 27,241 families living in the county. The population density was 89.8 people per square mile (34.7 people/km2). There were 43,450 housing units at an average density of 38.1 units per square mile (14.7 units/km2). The racial makeup of the county was 88.9% White, 1.5% Asian, 1.5% American Indian, 0.6% black or African American, 0.2% Pacific islander, 3.5% from other races, and 3.7% from two or more races. Those of Hispanic or Latino origin made up 7.8% of the population. In terms of ancestry, 24.4% wereGerman, 15.0% wereIrish, 12.3% wereEnglish, 6.2% wereNorwegian, and 5.4% wereAmerican.
Of the 40,244 households, 31.8% had children under the age of 18 living with them, 50.2% were married couples living together, 11.8% had a female householder with no husband present, 32.3% were non-families, and 25.8% of all households were made up of individuals. The average household size was 2.51 and the average family size was 2.99. The median age was 40.2 years.
The median income for a household in the county was $45,877 and the median income for a family was $55,002. Males had a median income of $48,329 versus $32,438 for females. The per capita income for the county was $22,948. About 11.8% of families and 16.9% of the population were below thepoverty line, including 23.3% of those under age 18 and 7.1% of those age 65 or over.
The county had been reliably Democratic in Presidential elections for over three decades, andWalter Mondale won this county inRonald Reagan's 49-state landslide in 1984.Donald Trump won a majority of the vote in 2016, 2020, and 2024, becoming the first Republican to win this county since Reagan in 1980.
United States presidential election results for Cowlitz County, Washington[22][23][24][25][26]