Population
35,297
2025
+13.6% since 2020
Source: U.S. Census Bureau, Population Estimates Program (Vintage 2025), 2025. Resident population, July 1 estimate.
Jefferson County had an estimated 35,297 residents in 2025, up 13.6% (4,217 more people) since 2020. That is faster than Idaho as a whole (+9.8%), and the 5th fastest growth of 43 counties in Idaho.
Data as of 2025 · updated
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35,297
2025
+13.6% since 2020
Source: U.S. Census Bureau, Population Estimates Program (Vintage 2025), 2025. Resident population, July 1 estimate.
+224
2025
6.3 per 1,000 residents
+2,950 in total, 2021–2025
Source: U.S. Census Bureau, Population Estimates Program (Vintage 2025), 2025. People moving in from other U.S. counties minus people moving out.
2.9%
2025
+0.7 pts since 2019
Source: U.S. Bureau of Labor Statistics, Local Area Unemployment Statistics, 2025. Annual average unemployment rate.
312
2025
−17.2% since 2021
8.8 per 1,000 residents
Source: U.S. Census Bureau, Building Permits Survey, 2025. Housing units authorized by building permits in the year.
$86,679
2020–24
+32.2% since 2016–20
Source: U.S. Census Bureau, American Community Survey 5-year estimates, 2020–24. American Community Survey 5-year estimate.
5,599
2023
+33.9% since 2018
Source: U.S. Census Bureau, County Business Patterns, 2023. Paid employees of private employers in mid-March (County Business Patterns).
Net domestic migration added 224 people in 2025: more people moved in from other U.S. counties than moved out.
Private employers had 5,599 paid employees in mid-March 2023, +33.9% since 2018 (County Business Patterns).
Unemployment averaged 2.9% in 2025, 0.7 points higher than in 2019 (before the pandemic).
Builders were authorized to start 312 new homes in 2025, or 8.8 per 1,000 residents.
Median household income was $86,679 in the 2020–24 American Community Survey, +32.2% since 2016–20.
Across the 3,107 U.S. counties with a comparable estimate, its population growth ranks 99th.
Part of the Idaho Falls, ID metro area.
Email me when Jefferson County gets new Census numbers: population, building permits, jobs and income. About 4 emails a year, one click to stop.
| Year | Population | Change |
|---|---|---|
| 2025 | 35,297 | +441 |
| 2024 | 34,856 | +560 |
| 2023 | 34,296 | +938 |
| 2022 | 33,358 | +1,151 |
| 2021 | 32,207 | +1,127 |
| 2020 | 31,080 | – |
Census Bureau population estimates, July 1 of each year.
Jefferson County grew by 4,217 people since 2020; the largest part came from domestic migration (+2,950).
| Component | 2025 | 2020–25 | Share |
|---|---|---|---|
| Natural changebirths minus deaths | +212 | +1,029 | |
| International migrationfrom and to other countries | +4 | +235 | |
| Domestic migrationfrom and to other U.S. counties | +224 | +2,950 | |
| Census adjustmentbalancing residual | +1 | +3 | |
| Total change | +441 | +4,217 |
Census Bureau population estimates, components of change, each year July 1 to June 30. The components add up to the change in the estimate; the Census adjustment is the small balancing figure the Bureau publishes.
| Measure | In Idaho | Among U.S. counties |
|---|---|---|
| Population growth | 5th of 43 | 99th of 3,107 |
| Net domestic migration per 1,000 residents | 18th of 43 | 898th of 3,108 |
| Private-sector job growth | 4th of 43 | 63rd of 3,092 |
| Median household income | 4th of 43 | 383rd of 3,107 |
| Lowest unemployment rate | 2nd of 43 | 303rd of 3,108 |
| New homes permitted per 1,000 residents | 13th of 43 | 200th of 3,005 |
1st = highest (lowest for unemployment). Counties are ranked only against others with a figure for the same period.
The County Growth and Demographics Report for Jefferson County, ID as a PDF, from federal data: population and migration, housing and rents, permits, private employers and jobs, unemployment, ranks in the state and the country, and neighbouring counties, with a source next to every number. Pay once, no subscription.
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Jefferson County grew faster than all 5 of its neighbouring counties with a comparable figure (+13.6%, 2020–25).
Its median household income ($86,679, 2020–24) is higher than in all 6 of its neighbouring counties.
| County | Population2025 | Population change2020–25 | Net domestic migration per 1,000 residents2025 | Homes permitted per 1,000 residents2025 | Median household income2020–24 |
|---|---|---|---|---|---|
| Jefferson County, ID This county | 35,297 | +13.6% | 6.3 | 8.8 | $86,679 |
| Clark County, ID | 783 | – | – | – | $55,208 |
| Bingham County, ID | 51,153 | +6.4% | −0.9 | 4.0 | $77,878 |
| Madison County, ID | 55,172 | +4.2% | −14.0 | 15.3 | $60,160 |
| Butte County, ID | 2,783 | +7.8% | 25.2 | 3.2 | $53,015 |
| Fremont County, ID | 14,208 | +5.9% | −14.5 | 11.0 | $72,683 |
| Bonneville County, ID | 135,771 | +8.9% | 8.9 | 9.0 | $79,068 |
Census Bureau population estimates and building permits, American Community Survey 5-year income. Rates per 1,000 residents. – means no figure, or a base too small for a change or rate (it would swing on a few people). A figure from another period shows its year and is left out of the comparison.
Yes. Its population grew 13.6% between 2020 and 2025, about 4,217 more people (Census Bureau population estimates). Idaho as a whole changed +9.8% over the same years. That ranks 5th of 43 counties in Idaho for population growth.
On net, about 224 people in 2025: that many more moved in from other U.S. counties than moved out (Census Bureau net domestic migration estimate).
It averaged 2.9% in 2025 (BLS Local Area Unemployment Statistics, annual average).
About 35,297 people, according to the U.S. Census Bureau's population estimate for July 1, 2025.
Private employers there had 5,599 paid employees in mid-March 2023, +33.9% since 2018 (Census Bureau County Business Patterns; government jobs and the self-employed are not counted).
Map, parcel and listing layers cover North and South Carolina only for now. This page and the other Idaho county pages carry the public federal growth figures.
Email me when Jefferson County gets new Census numbers: population, building permits, jobs and income. About 4 emails a year, one click to stop.
Each number shows its own period. Changes compare the latest period with five years earlier (or the earliest period available). Beacon CRE last refreshed these figures on 2026-11-05. Figures come from public federal statistics and are informational only, not investment advice. Check the source before relying on a number. Methodology: how we compute every number. More on every layer: data sources and licences.
Jobs outside North and South Carolina use County Business Patterns (paid private-sector employees in mid-March); wages and government jobs are not included.