Lewis and Clark County, Montana Population 2026
Updated April 2026 · US Census ACS 2023 5-Year Estimates · 6th-largest in Montana
The population of Lewis and Clark County, Montana is 72,580 as of the 2023 American Community Survey, making it the 6th-largest county in Montana. The median household income is $74,543, the median home value is $358,200, and the median age is 41.3.
The population of Lewis and Clark County has grown 18.2% since 2010 (63,578 → 75,129), a +1.20% annualized rate.
72,580
Population
+1.20%
Annual growth
21
People / sq mi
$74,543
Median Income
$358,200
Median Home Value
Lewis and Clark County covers 3,458 sq mi of land at 21.0 people per square mile.
About Lewis and Clark County, MT
Lewis and Clark County is defined demographically by education — 42.8% of adults hold a bachelor’s degree, above the national average. With 72,580 residents, Lewis and Clark County is a county in Montana. It is the #6-largest of all counties in Montana nationally.
Median household income is $74,543, below the US median of $78,538. Very few residents live in poverty — 4.4%, below the national 12.4%. Home prices are steep, with the typical property valued at $358,200, with typical rent around $1,062.
The population is unusually well-credentialed for US counties — 42.8% of adults have a four-year degree, above the national 35.0%. About 12.9% of workers primarily work from home, below the national 14.0%, and the average commute runs about 18 minutes each way.
The education numbers are the throughline: a college-heavy population in Lewis and Clark County usually coincides with higher incomes and a workforce concentrated in professional and information industries.
Lewis and Clark County Population History (2010-2024)
The county of Lewis and Clark County had a population of 63,578 in 2010 and 75,129 in 2024, a 18.2% growth over 14 years. The peak was 75,129 in 2024. Average annual growth rate: 1.20%.
75,129
Population (2024)
63,578
Population (2010)
75,129
Peak (2024)
1.20%
Avg Annual Growth
| Year | Population |
|---|---|
| 2010 | 63,578 |
| 2011 | 64,284 |
| 2012 | 64,760 |
| 2013 | 65,277 |
| 2014 | 65,764 |
| 2015 | 66,308 |
| 2016 | 67,001 |
| 2017 | 67,988 |
| 2018 | 68,775 |
| 2019 | 69,578 |
| 2020 | 71,179 |
| 2021 | 72,517 |
| 2022 | 73,681 |
| 2023 | 74,812 |
| 2024 | 75,129 |
Race & Ethnicity
| White | 91.5% |
| Black or African American | 0.6% |
| Asian | 0.0% |
| Hispanic or Latino (any race) | 3.7% |
| Two or More Races | 0.0% |
Age & Sex
41.3
Median Age
50.3%
Female
49.7%
Male
19.9%
Age 65+
Age Distribution
Children (under 15): 17.7% · Seniors (65+): 19.9%
Income & Poverty
| Median household income | $74,543+$4,621 vs state |
| Mean household income | $100,531 |
| Per-capita income | $43,263 |
| Poverty rate | 4.4%-2.7% vs state |
| Unemployment rate | 2.2% |
| Employment-to-population | 60.8% |
Top Industries by Employment
The largest employment sector in Lewis and Clark County is professional & business services, accounting for 25.4% of workers.
How residents commute
0.2%
Drive alone
4.8%
Carpool
69.2%
Public transit
12.9%
Work from home
17.5 min
Avg commute
Housing
$358,200+$20,100 vs state
Median home value
$1,062
Median rent
69.7%
Homeownership rate
33,837
Total housing units
90.6%
Occupied
9.4%
Vacant
30.3%
Renter-occupied
Social & access
93.8%
With health insurance
94.2%
With broadband internet
44.7%
Foreign-born
10.4%
Veterans (18+)
14.5%
With a disability
96.9%
Speak language other than English at home
Education
94.9%
High School+
42.8%
Bachelor's+
Largest cities in Montana
Other counties in Montana
Part of Montana
Metro areas in Montana
County rankings
Frequently Asked Questions
Lewis and Clark County, Montana has a population of 72,580 according to the US Census Bureau's 2023 American Community Survey 5-year estimates, making it the 6th-largest county in Montana. Population density is 21 people per square mile.
The population of Lewis and Clark County has grown 18.2% since 2010 (63,578 → 75,129), a +1.20% annualized rate.
The median household income in Lewis and Clark County, Montana is $74,543, with mean (average) household income of $100,531 and per-capita income of $43,263. 4.4% of residents live below the federal poverty level.
In Lewis and Clark County, the largest racial and ethnic groups are White (91.5%), Hispanic or Latino (3.7%), Black or African American (0.6%). Figures are from the US Census Bureau's 2023 ACS 5-year estimates and reflect self-reported responses.
The median age in Lewis and Clark County, Montana is 41.3 years. Residents are 50.3% female and 49.7% male.
The median home value in Lewis and Clark County is $358,200 and median monthly rent is $1,062. 69.7% of occupied housing units are owner-occupied. The county has 33,837 total housing units, 9.4% of which are vacant.
The largest employment sector in Lewis and Clark County, Montana is professional, scientific, and management services, employing 25.4% of workers. The unemployment rate is 2.2%.
Billings is among the largest cities associated with Lewis and Clark County, Montana, with a population of 118,321.
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Population, race, income, age, and trends across Montana
Data from the American Community Survey (ACS) 5-Year estimates.
Source: U.S. Census Bureau ACS, 2026.