Missoula County
County
Missoula County Courthouse
Location within the U.S. state of Montana
Montana's location within the U.S.
Coordinates: 47°02′N 113°56′W / 47.04°N 113.93°W / 47.04; -113.93
Country	United States
State	Montana
Founded	December 14, 1860
Seat	Missoula
Largest city	Missoula
Area
• Total	2,618 sq mi (6,780 km2)
• Land	2,593 sq mi (6,720 km2)
• Water	25 sq mi (60 km2)  1.0%
Population  (2020)
• Total	117,922
• Estimate  (2022)	121,041
• Density	45/sq mi (17/km2)
Time zone	UTC−7 (Mountain)
• Summer (DST)	UTC−6 (MDT)
Congressional district	1st
Website	www.missoulacounty.us
Montana county number 04

Missoula County /mɪˈzuːlə/ ^ⓘ is a county located in the State of Montana. As of the 2020 census, the population was 117,922,^[1] making it Montana's third most populous county. Its county seat and most populous city is Missoula.^[2] The county was founded in 1860.^[3]

Missoula County comprises the Missoula, MT Metropolitan Statistical Area.

Missoula County, Washington Territory was incorporated in 1860, when this area was still part of Washington Territory.^[4][3] Missoula County encompassed present-day Missoula and Deer Lodge Counties, as well as a large area of land north and south of present-day Missoula County. Hell Gate Town, the county seat, was at the confluence of the Clark Fork and Bitterroot Rivers.

The area encompassing today's Missoula County became part of the United States as a result of Oregon Treaty of June 14, 1846. It was part of the Oregon Territory's Clark County, which replaced the District of Vancouver September 3, 1844. The territory was divided on March 2, 1853, with Clark County becoming part of the new Washington Territory. Clark County was divided the next year to create Skamania County, which a month later was divided to create Walla Walla County, which was further divided in 1858 to create Spokane County.^[5] On December 14, 1860, Missoula County was carved out of Spokane County with the first county seat at Hell Gate. The county made up the region between modern-day Idaho and the Continental Divide north of the 46th parallel.^[6] When Idaho Territory was created in 1863 it adopted Missoula County as the territory's 3rd county on January 16, 1864, with more or less the same boundaries and Wordensville (present Missoula) established as the county seat.^[7][8] This first county consisted of all or part of current Ravalli, Missoula, Granite, Deer Lodge, Silver Bow, Powell, Mineral, Lake, Sanders, Lincoln, Flathead, and Glacier Counties.

Missoula County became a part of Montana Territory when the territory was organized out of the existing Idaho Territory by Act of Congress and signed into law by President Abraham Lincoln on May 26, 1864. At this time Deer Lodge County (today Deer Lodge, Granite, Silver Bow, and Powell Counties) was cut out of Missoula.^[9] The creation of Flathead (today Flathead and Lincoln Counties) and Ravalli Counties in 1893, Powell in 1901, Sanders in 1905, Mineral in 1914 and finally Lake County in 1923 gave Missoula its present borders.^[10]

According to the United States Census Bureau, the county has a total area of 2,618 square miles (6,780 km²), of which 2,593 square miles (6,720 km²) is land and 25 square miles (65 km²) (1.0%) is water.^[11] It is the 24th largest county in Montana.

Five large valleys and two major rivers wind through this mountainous region.

Located in the Northern Rockies, Missoula County has a typical Rocky Mountain ecology. Local wildlife includes white-tailed deer, black bears, osprey, and bald eagles. During the winter months, rapid snow melt on Mount Jumbo due to its steep slope leaves grass available for grazing elk and mule deer. The rivers around Missoula provide nesting habitats for bank swallows, northern rough-winged swallows and belted kingfishers. Killdeer and spotted sandpipers can be seen foraging insects along the gravel bars. Other species include song sparrows, catbirds, several species of warblers, and the pileated woodpecker. The rivers also provide cold, clean water for native fish such as westslope cutthroat trout and bull trout. The meandering streams also attract beaver and wood ducks.^[12]

Native riparian plant life includes sandbar willows and cottonwoods, and Montana's state tree, the ponderosa pine. Other native plants include wetland species such as cattails and beaked-sedge as well as shrubs and berry plants like Douglas hawthorn, chokecherry, and western snowberries.^[12] Missoula is also home to several noxious weeds which multiple programs have tried to eliminate. Notable ones include Dalmatian toadflax, spotted knapweed, leafy spurge, St. John's wort, and sulfur cinquefoil.^[13] The Norway maples that line many of Missoula's older streets have also been declared an invasive species.^[14]

Missoula County has a semi-arid climate (Köppen climate classification BSk), with cold and moderately snowy winters, hot and dry summers, and spring and autumn are short and crisp in between. Winter conditions are usually far milder than much of the rest of the state due to its western position within the state. However, the mildness is also induced by the dampness, as unlike much of the rest of the state, precipitation is not at a strong minimum during winter. Winter snowfall averages 43 inches (109 cm), with most years seeing very little of it from April to October. Summers see very sunny conditions, with highs peaking at 84 °F (28.9 °C) in July. However, temperature differences between day and night are large during this time and from April to October, due to the relative aridity.^[15][16]

• Jefferson Lines
• Mountain Line

As of the 2020 census, there were 117,922 people living in the county.^{[citation needed]}

As of the 2010 census, there were 109,299 people, 45,926 households, and 25,931 families residing in the county. The population density was 42.1 inhabitants per square mile (16.3/km²). There were 50,106 housing units at an average density of 19.3 per square mile (7.5/km²). The racial makeup of the county was 92.7% white, 2.6% American Indian, 1.1% Asian, 0.4% black or African American, 0.1% Pacific islander, 0.4% from other races, and 2.6% from two or more races. Those of Hispanic or Latino origin made up 2.6% of the population. In terms of ancestry, 26.1% were German, 17.8% were Irish, 12.3% were English, 7.3% were Norwegian, and 5.4% were American.

Of the 45,926 households, 26.5% had children under the age of 18 living with them, 42.9% were married couples living together, 9.2% had a female householder with no husband present, 43.5% were non-families, and 30.3% of all households were made up of individuals. The average household size was 2.30 and the average family size was 2.88. The median age was 34.3 years.

The median income for a household in the county was $42,887 and the median income for a family was $58,302. Males had a median income of $39,603 versus $30,069 for females. The per capita income for the county was $24,343. About 8.8% of families and 17.3% of the population were below the poverty line, including 14.9% of those under age 18 and 8.8% of those age 65 or over.

Missoula County has a diverse economy as a growing regional trade center with several major employers such as the University of Montana, regional hospitals, and the U.S. Forest Service each employing thousands. However, 90% of wage and salary workers work for small businesses with under 20 workers with a quarter of them self-employed.^[25]

Missoula County is governed by a Board of County Commissioners of three members; each serving six-year terms staggered so as to have one election every two years. The commission has authority over all legislative, executive, and administrative issues throughout the county not specifically reserved by law or ordinance to other elected officials.^[26]

Originally a swing county, Missoula County has voted reliably Democratic since 2004, and has voted Republican only once since 1988. In 2000, Republican George W. Bush won the county by a 9% margin while Green Party candidate Ralph Nader received over 16% of the vote in the county. This is most likely due to the city of Missoula being home to the University of Montana.