How many people live in Lewis and Clark County, MT?
Updated Apr. 6, 2026Refreshed annually
In 2024, there were about 75,100 people living in Lewis and Clark County, MT. That makes Lewis and Clark County the sixth-most populous county in Montana. It is home to 6.6% of people living in the state.
75.1K
population of Lewis and Clark County, MT (2024)
6.6%
County share of the Montana population (2024)
About 75,100 people lived in Lewis and Clark County, MT in 2024.
Population estimates, 2000–2024
What are Lewis and Clark County, MT’s age demographics?
About 16,100 Lewis and Clark County, MT residents are aged 65 and older in 2024. That represents 21.4% of its population. For comparison, the age group represents 21.1% of Montana’s population and 18% in the US overall.
Another 15,500 Lewis and Clark County, MT residents, or 20.7% of the population, were children under 18. For comparison, the age group represents 20.5% of Montana’s population and 21.6% in the US overall.
A higher share of Lewis and Clark County, MT's population is aged 65 or older than the US as a whole.
Population estimates by age group, (2024)
What are Lewis and Clark County, MT’s racial and ethnic demographics?
Non-Hispanic white residents make up 90.1% of the Lewis and Clark County population, higher than the national share of 57.5%. Lewis and Clark County also has a larger share of people identifying as non-Hispanic American Indian and Alaska Native (1.8%) than the US overall (0.72%).
In contrast, Lewis and Clark County’s Hispanic population accounts for 4.3%, below the 20% nationwide, and the non-Hispanic Black or African American population makes up 0.48% of the county, compared with 12.6% nationally.
Racial and ethnic make up differ based on location. These figures reflect how people identified their race alone (not in combination with other races), and separate out Hispanic or Latino ethnicity, following Census reporting standards.
Lewis and Clark County, MT has a higher share of a non-Hispanic white population than Montana as a whole.
Population estimates by race and ethnicity, (2024)
The largest city or town in Lewis and Clark County, MT is Helena with about 34,700 residents in 2024.
Cities and towns in Lewis and Clark County, MT ranked by population
Population (2024), includes only portions within county
| City or town | Population | |
|---|---|---|
| 1. | Helena | 34,729 |
| 2. | East Helena | 2,239 |
| 3. | Balance of Lewis and Clark County | 38,161 |
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Methodology
USAFacts standardizes data, in areas such as time and demographics, to make it easier to understand and compare.
The analysis was generated with the help of AI and reviewed by USAFacts for accuracy.
Page sources
USAFacts endeavors to share the most up-to-date information available. We sourced the data on this page directly from government agencies; however, the intervals at which agencies publish updated data vary.
