• county
  • FIPS 30043
  • Largest town: Boulder

Jefferson County, Montana

Jefferson County had 13,304 residents in the Census Vintage 2024 estimate, on 1,657.0 square miles of land. It ranks 15th of 56 in Montana by population and 42nd by land area.

Population
13,304
#15 of 56 in Montana · #2,205 in US
Area
1,657.0 sq mi
#42 of 56 in Montana · #365 in US
Density
8.0 / sq mi
#11 of 56 in Montana · #2,640 in US
Median household income
$85,163
#2 of 56 in Montana · #328 in US

Census Vintage 2024 estimates · SAIPE 2023 income · 2024 Gazetteer land area

Jefferson County within Montana. Pin: Helena.

Measure from here

Tools and pages that start from Jefferson County

Jefferson County population, land area and income

Jefferson County had 13,304 residents in the Census Vintage 2024 estimate, on 1,657.0 square miles of land. It ranks 15th of 56 in Montana by population and 42nd by land area. That works out to 8.0 people per square mile, below the US average of 96.3, and in the bottom quarter nationally.

The median county-equivalent in Montana has 7,814 residents; Jefferson County is somewhat larger.

Its SAIPE 2023 median household income of $85,163 is in the top quarter among 3,143 counties with an estimate.

National rank among 3,144

Population

13,304

3144th1st

2205th of 3,144 (US)

Land area

1,657 sq mi

3144th1st

365th of 3,144 (US)

Density

8.0 / sq mi

3144th1st

2640th of 3,144 (US)

Median household income

$85,163

3143rd1st

328th of 3,143 (US)

Rank within Montana (56)

Population

13,304

56th1st

15th of 56 (MT)

Land area

1,657 sq mi

56th1st

42nd of 56 (MT)

Density

8.0 / sq mi

56th1st

11th of 56 (MT)

Median household income

$85,163

56th1st

2nd of 56 (MT)

How Jefferson County's population changed since 2020

Jefferson County gained 1,162 residents between the July 2020 and July 2024 estimates, a rise of 9.6%. That ranks 7th of 56 in Montana for growth. The median Montana county changed by +2.8%, and the state as a whole by +4.6%.

Since the April 2020 estimates base, Jefferson County recorded 460 births and 634 deaths, a natural change of -174. Net international migration added +38 and net domestic migration, people moving to or from other US counties, came to +1,365. The largest single component was domestic migration, which added 1,365 people.

12.1k202012.5k202112.9k202213.1k202313.3k2024
Census Vintage 2024 county estimates for July 1 of each year. The axis starts above zero so year-to-year changes are visible.

Components of change, April 2020 to July 2024

Births
460
Deaths
634
Net international migration
+38
Net domestic migration
+1,365
Change, July 2023 to July 2024
+218

Where Jefferson County is

The Census internal point of Jefferson County is at 46.124200, -112.059400. It sits in UTM zone 12N. The map shades Montana's 56 county-equivalents by population change from 2020 to 2024, darker for faster growth, with Jefferson County outlined. Dots are towns of 1,000+ people with residents in it.

Liberty County: -1.2%Golden Valley County: +5.1%Dawson County: -2.1%Flathead County: +9.2%Beaverhead County: +6.7%Prairie County: +2.0%Garfield County: +0.9%Lewis and Clark County: +5.5%Sweet Grass County: +2.4%Wheatland County: -0.7%Ravalli County: +8.5%Jefferson County: +9.6%Carter County: -0.6%Chouteau County: -0.6%Custer County: +0.9%Teton County: +3.1%Granite County: +9.0%Deer Lodge County: +4.1%Cascade County: +0.1%Powder River County: +2.4%Meagher County: +7.3%Daniels County: -1.7%Glacier County: -1.8%Wibaux County: -2.7%Fallon County: -2.7%McCone County: -0.7%Sheridan County: -2.5%Missoula County: +3.5%Toole County: +3.7%Sanders County: +11.5%Roosevelt County: -5.6%Rosebud County: -1.3%Treasure County: -2.5%Yellowstone County: +3.9%Blaine County: -1.4%Musselshell County: +14.8%Broadwater County: +21.0%Powell County: +2.6%Fergus County: +3.4%Phillips County: +0.1%Gallatin County: +6.2%Silver Bow County: +2.6%Madison County: +12.6%Richland County: -4.4%Lake County: +6.9%Valley County: -1.7%Judith Basin County: +4.3%Hill County: -1.2%Big Horn County: -2.2%Stillwater County: +5.0%Carbon County: +9.4%Mineral County: +13.7%Petroleum County: +4.6%Pondera County: +3.4%Park County: +4.9%Lincoln County: +12.4%
Change 2020 to 2024
  1. < -1.4%
  2. < +0.9%
  3. < +3.9%
  4. < +7.3%
  5. ≥ +7.3%
no data

Orange pin: Jefferson County internal point. Dark pin: Helena.

Internal point

Decimal
46.124200, -112.059400
DMS
46°07'27.12"N 112°03'33.84"W
UTM
12N 418152.1E 5108392.6N
Geohash
c80q6h8uf
Plus code
85R94WFR+M6

Towns in Jefferson County

2 incorporated places of 1,000+ people have residents in Jefferson County, 2,421 people together, or 18% of the county. Each figure counts only the part of the town inside Jefferson County; towns marked "part" extend into another county. The largest is Boulder with 1,305.

  1. 01Boulder1,305
  2. 02Whitehall1,116
Census Vintage 2024 subcounty estimates, county parts of incorporated places (SUMLEV 157).

Counties bordering Jefferson County

The Census 2024 county adjacency file lists 7 neighbors for Jefferson County. The most populous is Gallatin County, MT, with 126,984 residents. Distances run between Census internal points in a straight line.

Distance to Helena and the nearest big city

Helena is 32.0 miles N of Jefferson County's internal point in a straight line. The nearest place of 100,000 or more is Billings, MT (population 121,483), 170.0 miles away. The nearest place of 10,000 or more is Helena, MT (population 34,729), 32.7 miles away.

Jefferson County FIPS code

The FIPS code of Jefferson County is 30043: state code 30 for Montana plus county code 043. Use it as text, with the leading zero, when joining Census, BLS, or CDC county tables. SAIPE lists its 2023 median household income as $85,163.

Questions people ask

What is the population of Jefferson County, Montana?

The Census Vintage 2024 estimate for July 1, 2024 is 13,304. That is up 1,162 people (9.6%) from the July 2020 estimate of 12,142.

What is the FIPS code of Jefferson County?

30043. The first two digits (30) are Montana; the last three (043) identify the county.

What is the largest town in Jefferson County?

Boulder, with 1,305 residents inside Jefferson County in 2024.

Which counties border Jefferson County?

7 county-equivalents border it in the Census 2024 adjacency file: Gallatin County, MT; Lewis and Clark County, MT; Silver Bow County, MT; Deer Lodge County, MT; Madison County, MT; Broadwater County, MT; Powell County, MT.

Sources and data as of

Data as of: Census Vintage 2024 population estimates, 2024 Gazetteer land area and internal points, SAIPE 2023 median household income.

  1. 01Census Vintage 2024 county population estimates
  2. 02Census 2024 Gazetteer, counties
  3. 03Census SAIPE 2023 state and county estimates
  4. 04Census Vintage 2024 subcounty population estimates
  5. 05Census 2024 county adjacency file
  6. 06Census 2024 cartographic boundary file, counties (1:5,000,000)

How every number is computed: methodology. Spotted a wrong figure? Report an error.