Lewis and Clark County is a county located in the U.S. state of Montana. As of the 2020 census, the population was 70,973. Its county seat is Helena, the state capital. The numerical designation for Lewis and Clark County (used in the issuance of the state's license plates) is 5. The county was established on June 2, 1865, as one of the nine original counties of the Territory of Montana named Edgerton County in honor of Sidney Edgerton, first Governor of the Territory of Montana, and was renamed Lewis and Clark County on March 1, 1868, in honor of explorers Meriwether Lewis and William Clark. Lewis and Clark County is part of the Helena, Montana Micropolitan Statistical Area.

Geography

According to the United States Census Bureau, the county has a total area of 3498 sqmi, of which 3459 sqmi is land and 39 sqmi (1.1%) is water.

Major highways

Adjacent counties

National protected areas

Demographics

2020 census

As of the 2020 census, there were 70,973 people living in the county.

2010 census

As of the 2010 census, there were 63,395 people, 26,694 households, and 16,705 families in the county. The population density was 18.3 PD/sqmi. There were 30,180 housing units at an average density of 8.7 /sqmi. The racial makeup of the county was 94.0% white, 2.1% American Indian, 0.6% Asian, 0.3% black or African American, 0.1% Pacific islander, 0.5% from other races, and 2.4% from two or more races. Those of Hispanic or Latino origin made up 2.5% of the population. In terms of ancestry, 29.2% were German, 19.3% were Irish, 15.0% were English, 8.9% were Norwegian, and 5.1% were American. Of the 26,694 households, 28.8% had children under the age of 18 living with them, 49.0% were married couples living together, 9.4% had a female householder with no husband present, 37.4% were non-families, and 30.7% of all households were made up of individuals. The average household size was 2.30 and the average family size was 2.87. The median age was 40.9 years. The median income for a household in the county was $50,238 and the median income for a family was $65,573. Males had a median income of $44,476 versus $34,893 for females. The per capita income for the county was $25,894. About 5.8% of families and 9.7% of the population were below the poverty line, including 10.2% of those under age 18 and 4.1% of those age 65 or over.

Politics

Lewis and Clark County leans slightly Republican, but it has voted for Democratic candidates three times since 1964. Bill Clinton won by nearly seven percentage points in 1992, but Bob Dole won by 130 votes in 1996. Barack Obama carried the county in 2008 but lost it to Mitt Romney in 2012. In recent elections, the county has voted Republican but only by narrow margins.

Communities

Cities

Census-designated places

Other unincorporated communities

Education

School districts include: K-12 (Unified): High school: Elementary school:

Notable people