Data / Population / Jefferson County

Population in Jefferson County

Population in Jefferson County was 15,291 in 2025, according to the U.S. Census Bureau. That is down 0.7% from 2024. That is the 48th highest of 99 counties in 2025.

2025, persons15,291
Change on 2024-0.7%
Rank48th of 99Counties in Iowa ranked
Series high15,7952021
Series low15,2912025

Population in Jefferson County, 2020 to 2025

CSVChart (SVG)

15.2K15.4K15.6K15.8K2020202120222023202420252020: 15,688 persons2021: 15,795 persons2022: 15,580 persons2023: 15,464 persons2024: 15,405 persons2025: 15,291 persons
persons. Source: U.S. Census Bureau. Retrieved 2026-10-08, published 2026-03-26.
All 6 values
Periodpersons
202515,291
202415,405
202315,464
202215,580
202115,795
202015,688

Compared with Iowa and United States

Place2025
Jefferson County15,291
Iowa3,238,387
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 15,291 in 2025, according to the U.S. Census Bureau. That is down 0.7% from 2024. That is the 48th highest of 99 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?

15,795 in 2021, the highest value since 2020 in this series.

More statistics for Jefferson County

All statistics for Jefferson County