Data / Population / Jefferson County

Population in Jefferson County

Population in Jefferson County was 13,329 in 2025, according to the U.S. Census Bureau. That is up 0.7% from 2024. That is the 15th highest of 56 counties in 2025.

2025, persons13,329
Change on 2024+0.7%
Rank15th of 56Counties in Montana ranked
Series high13,3292025
Series low12,1412020

Population in Jefferson County, 2020 to 2025

CSVChart (SVG)

12K12.3K12.5K12.8K13K13.3K13.5K2020202120222023202420252020: 12,141 persons2021: 12,465 persons2022: 12,846 persons2023: 13,049 persons2024: 13,231 persons2025: 13,329 persons
persons. Source: U.S. Census Bureau. Retrieved 2026-10-08, published 2026-03-26.
All 6 values
Periodpersons
202513,329
202413,231
202313,049
202212,846
202112,465
202012,141

Compared with Montana and United States

Place2025
Jefferson County13,329
Montana1,144,694
United States341,784,857

Rankings

Definition

Resident population. Spain and the EU: 1 January, with Spanish figures from the official municipal register (Padrón). United States: Census Bureau population estimates for 1 July. Other countries and the World: World Bank mid-year estimates, which count all residents regardless of legal status or citizenship.

For Denmark, Statistics Denmark counts the registered resident population on 1 January. Greenland and the Faroe Islands are excluded. The annual series selects the first-quarter reference date from FOLK1A. The World Bank series exists for every country, so use it (through compare) to rank countries on one basis.

How to cite

U.S. Census Bureau. Annual estimates of the resident population for the United States, states and counties, 1 July (Population Estimates Program). https://www2.census.gov/programs-surveys/popest/datasets/2020-2025/. Retrieved 2026-10-08.

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Questions

What is the population in Jefferson County?

Population in Jefferson County was 13,329 in 2025, according to the U.S. Census Bureau. That is up 0.7% from 2024. That is the 15th highest of 56 counties in 2025.

Where does this figure come from?

U.S. Census Bureau. Annual estimates of the resident population for the United States, states and counties, 1 July (Population Estimates Program). Retrieved by Invokely on 2026-10-08.

What was the highest population in Jefferson County?

13,329 in 2025, the highest value since 2020 in this series.

More statistics for Jefferson County

All statistics for Jefferson County