County · Montana
Jefferson County, Montana
Jefferson County, Montana. Jefferson County had 13,329 residents in 2025 by the Census Bureau's estimate, up 10.3% since 2020, faster than Montana (+5.6%). It holds 10 places (2 cities, villages and boroughs and 8 census-designated) and 3 census tracts. GEOID 30043.
Jefferson County is one of the 3 counties of the Helena, MT metropolitan statistical area (the Census Bureau's July 2023 delineation).
Residents, July 2025 estimate
13,329
Census Bureau estimate (no margin published)
2020 Census count: 12,085 · ACS 2020-2024: 12,774
Median household income
$95,490
±$18,478 (90% margin)
Montana: $72,509
Median home value
$446,900
±$22,371 (90% margin)
Montana: $375,800
Median gross rent
$925
±$58 (90% margin)
Montana: $1,081
How many people live in Jefferson County, and is it growing?
The 2020 Census counted 12,085 residents in Jefferson County. The Census Bureau estimates 13,329 for July 1, 2025, up 10.3% since 2020, faster than Montana (+5.6%). The 2020-2024 American Community Survey puts the population at 12,774 over 1,657 square miles of land.
| Measure | Jefferson County | Montana | Change since 2015-2019 |
|---|---|---|---|
| Total population | 12,774 | 1,116,875 | +857 |
| Households | 4,996±136 | 458,859 | +512 |
| Average household size | 2.50±0.07 | 2.37 | −0.10 |
| Housing units | 5,407±27 | 528,419 | +295 |
Jefferson County's population since 2000
From 10,049 in 2000 to 13,329 in 2025: up 32.6%. The 2000, 2010 and 2020 figures are census counts. The 2005 figure is the Census Bureau's intercensal estimate, revised to fit the 2000 and 2010 counts and drawn on 2010 boundaries; 2015 and 2025 are July 1 estimates made from the census before them.
Source: The 2000, 2010 and 2020 Census counts and the Census Bureau's population estimates (intercensal 2000-2010, Vintage 2020, Vintage 2025) · Census population estimates
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026); PEP Vintage 2025 (CO-EST2025); 2020 Census · Check it at data.census.gov
What cities and towns are in Jefferson County?
Jefferson County holds 10 places: 2 cities, villages and boroughs (incorporated places) and 8 census-designated places. The largest is Montana City with 3,092 residents (2020-2024). Places that cross a county line are listed with the share of their 2020 residents who live in this county.
| Montana City | 2,918 | $129,755 |
|---|---|---|
| Clancy | 1,851 | $125,000 |
| Boulder | 1,201 | $72,500 |
| Whitehall | 1,006 | $44,844 |
| South HillsGEOID 3069725 | 644 | $168,235 |
| Jefferson CityGEOID 3039400 | 597 | $125,682 |
| Rader CreekGEOID 3060450 | 341 | $100,691 |
| BasinGEOID 3004150 | 199 | $46,597 |
| CardwellGEOID 3012400 | 62 | not published |
| ElkhornGEOID 3023865 | 12 | not published |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026); 2020 place-by-county parts · Check it at data.census.gov
Who lives in Jefferson County?
The median resident of Jefferson County is 47.1 years old; 20.0% are under 18 and 23.2% are 65 or older. The largest group is non-Hispanic white residents at 90.6%, then non-Hispanic residents of two or more races at 4.4%. 1.0% of residents were born outside the United States.
| Measure | Jefferson County | Montana | Change since 2015-2019 |
|---|---|---|---|
| Median age | 47.1±0.5 | 40.4 | no clear change |
| Under 18 years | 20.0%±0.2 pts | 21.0% | – |
| 65 years and over | 23.2%±0.3 pts | 20.1% | – |
| Hispanic or Latino (any race) | 3.0% | 4.6% | +0.4 pts |
| White alone, not Hispanic | 90.6%±0.5 pts | 83.6% | −2.1 pts |
| Black or African American alone, not Hispanic | 0.0%±0.1 pts | 0.4% | – |
| Asian alone, not Hispanic | 0.4%±0.2 pts | 0.8% | – |
| American Indian and Alaska Native alone, not Hispanic | 1.4%±0.7 pts | 5.3% | – |
| Native Hawaiian and Other Pacific Islander alone, not Hispanic | 0.0%±0.2 pts | 0.0% | – |
| Two or more races, not Hispanic | 4.4%±0.7 pts | 4.7% | – |
| Some other race alone, not Hispanic | 0.3%±0.3 pts | 0.5% | – |
| Born outside the United States | 1.0%±0.4 pts | 2.3% | no clear change |
| Speak a language other than English at home (age 5+) | 2.3%±0.9 pts | 4.2% | – |
| Civilian veterans (age 18+) | 10.4%±1.8 pts | 9.0% | – |
| With a disability | 17.7%±2.8 pts | 14.5% | – |
| No health insurance coverage | 5.8%±1.4 pts | 8.6% | no clear change |
| High school graduate or higher (age 25+) | 93.9%±1.7 pts | 94.6% | – |
| Bachelor's degree or higher (age 25+) | 32.2%±3.3 pts | 35.2% | no clear change |
| Graduate or professional degree (age 25+) | 12.4%±2.3 pts | 12.0% | – |
| Moved from another state in the past year | 0.9%±0.4 pts | 3.7% | – |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) (Data Profiles DP02, DP05) · Check it at data.census.gov
What do households in Jefferson County earn?
Half of Jefferson County's 4,996 households earn less than $95,490 a year (±$18,478), against $72,509 in Montana. In 2015-2019 it was $85,713 in 2024 dollars; the margins of error cannot tell the two periods apart. 5.7% of residents live below the poverty line.
| Measure | Jefferson County | Montana | Change since 2015-2019 |
|---|---|---|---|
| Median household income | $95,490±$18,478 | $72,509 | no clear change |
| Mean household income | $123,428±$10,042 | $98,908 | – |
| Per capita income | $49,303±$3,874 | $41,711 | +$8,969 |
| People below the poverty line | 5.7%±1.5 pts | 11.5% | no clear change |
| Children under 18 below the poverty line | 6.6%±3.5 pts | 12.7% | no clear change |
| Households receiving SNAP | 5.1%±1.7 pts | 7.8% | – |
| Households with a broadband subscription | 91.4%±2.9 pts | 89.4% | – |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) (Data Profile DP03) · Check it at data.census.gov
What does housing cost in Jefferson County?
Owners occupy 84.2% of Jefferson County's occupied homes and renters 15.8%. The median owner-occupied home is valued at $446,900 by its owner (±$22,371). The median renter pays $925 a month including utilities, and 17.0% of renters pay 35% or more of their income on rent.
| Measure | Jefferson County | Montana | Change since 2015-2019 |
|---|---|---|---|
| Median home value (owner-occupied) | $446,900±$22,371 | $375,800 | +$98,983 |
| Median gross rent | $925±$58 | $1,081 | no clear change |
| Renters paying 35% or more of income on rent | 17.0%±9.0 pts | 35.5% | no clear change |
| Median monthly owner costs, with a mortgage | $1,916±$160 | $1,798 | – |
| Owner-occupied homes | 84.2%±2.7 pts | 69.2% | no clear change |
| Housing units | 5,407±27 | 528,419 | +295 |
| Homeowner vacancy rate | 0.7%±0.6 pts | 0.9% | – |
| Rental vacancy rate | 2.7%±3.1 pts | 5.3% | – |
| Single-family detached homes | 83.2%±3.0 pts | 68.8% | – |
| Mobile homes | 11.3%±2.7 pts | 9.4% | – |
| Built 2020 or later | 3.4%±2.2 pts | 2.3% | – |
| Built 1939 or earlier | 10.1%±2.7 pts | 12.8% | – |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) (Data Profile DP04) · Check it at data.census.gov
How many new homes is Jefferson County building?
Builders took permits for 20 new housing units across Jefferson County in 2025 (11 single-family), 1.5 per 1,000 residents.
Source: Building Permits Survey, annual county files 2019-2025, U.S. Census Bureau · Census Building Permits Survey
How do people in Jefferson County get to work?
74.6% of Jefferson County's workers drive alone and 12.7% work from home. The average trip to work takes 24.4 minutes. The unemployment rate in 2020-2024 averaged 4.2%.
| Measure | Jefferson County | Montana | Change since 2015-2019 |
|---|---|---|---|
| In the labor force (age 16+) | 60.8%±2.5 pts | 62.9% | – |
| Unemployment rate | 4.2%±1.6 pts | 3.6% | no clear change |
| Drove alone to work | 74.6%±3.8 pts | 71.1% | – |
| Carpooled | 9.4%±2.8 pts | 9.7% | – |
| Public transportation | 0.0%±0.5 pts | 0.6% | – |
| Walked | 2.2%±1.2 pts | 3.9% | – |
| Worked from home | 12.7%±3.6 pts | 12.5% | +7.2 pts |
| Mean travel time to work | 24.4 min±1.8 | 19.1 min | +4.0 min |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) (Data Profile DP03) · Check it at data.census.gov
What are Jefferson County's census tracts?
Jefferson County is divided into 3 census tracts. Among those with a reliable estimate, median household income runs from $63,083 (Tract 9623) to $136,667 (Tract 9622.01).
| Tract 9622.0130043962201 | 4,371±328 | $136,667 |
|---|---|---|
| Tract 9622.0230043962202 | 4,948±346 | $80,375 |
| Tract 962330043962300 | 3,455±306 | $63,083 |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) · Check it at data.census.gov
How does Jefferson County compare with Montana's other counties?
| Measure | Rank |
|---|---|
| Population | 16th of 56 |
| Growth 2020-2025 | 10th of 56 |
| Residents per square mile | 11th of 56 |
| Median household income | 1st of 56 |
| Median home value | 7th of 56 |
| Median gross rent | 17th of 56 |
| Poverty rate | 54th of 56 |
| Bachelor's degree or higher | 13th of 56 |
| Median age | 19th of 56 |
Source: PlainCities ranks from the American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) and PEP Vintage 2025 · How ranks are computed
How these figures are made: methodology and release checks · reading a margin of error · every state · corrections
Not on this page: crime, weather and schools for Jefferson County are other agencies' records. Crime: the FBI's Crime Data Explorer · climate: NOAA's U.S. Climate Normals · schools: the National Center for Education Statistics' school search.