Jefferson County, Idaho Population 2026
Updated April 2026 · US Census ACS 2023 5-Year Estimates · 12th-largest in Idaho
The population of Jefferson County, Idaho is 32,234 as of the 2023 American Community Survey, making it the 12th-largest county in Idaho. The median household income is $82,952, the median home value is $335,000, and the median age is 32.3.
The population of Jefferson County has grown 32.9% since 2010 (26,222 → 34,854), a +2.05% annualized rate.
32,234
Population
+2.05%
Annual growth
29
People / sq mi
$82,952
Median Income
$335,000
Median Home Value
Jefferson County covers 1,094 sq mi of land at 29.5 people per square mile.
About Jefferson County, ID
Jefferson County skews on age — the median resident is 32.3, younger than the national median. With 32,234 residents, Jefferson County is a county in Idaho. It ranks #12 among counties in Idaho by population.
Households take in a median $82,952, comfortably above the US median of $78,538. About 7.4% of residents live below the federal poverty level, below the national 12.4%. The median home value is $335,000, with typical rent around $1,098.
College attainment is above the local norm at 27.2%, below the national 35.0%. Remote work is below the national 14.0% at 7.3%, and the average commute runs about 25 minutes each way.
Jefferson County Population History (2010-2024)
The county of Jefferson County had a population of 26,222 in 2010 and 34,854 in 2024, a 32.9% growth over 14 years. The peak was 34,854 in 2024. Average annual growth rate: 2.06%.
34,854
Population (2024)
26,222
Population (2010)
34,854
Peak (2024)
2.06%
Avg Annual Growth
| Year | Population |
|---|---|
| 2010 | 26,222 |
| 2011 | 26,315 |
| 2012 | 26,642 |
| 2013 | 26,809 |
| 2014 | 26,948 |
| 2015 | 27,133 |
| 2016 | 27,827 |
| 2017 | 28,448 |
| 2018 | 29,418 |
| 2019 | 29,918 |
| 2020 | 31,082 |
| 2021 | 32,208 |
| 2022 | 33,365 |
| 2023 | 34,259 |
| 2024 | 34,854 |
Race & Ethnicity
| White | 88.3% |
| Black or African American | 0.1% |
| Asian | 0.0% |
| Hispanic or Latino (any race) | 2.4% |
| Two or More Races | 0.0% |
Age & Sex
32.3
Median Age
48.7%
Female
51.3%
Male
11.5%
Age 65+
Age Distribution
Children (under 15): 26.7% · Seniors (65+): 11.5%
Income & Poverty
| Median household income | $82,952+$8,316 vs state |
| Mean household income | $95,822 |
| Per-capita income | $30,733 |
| Poverty rate | 7.4%+0.4% vs state |
| Unemployment rate | 1.6% |
| Employment-to-population | 64.5% |
Top Industries by Employment
The largest employment sector in Jefferson County is professional & business services, accounting for 24.0% of workers.
How residents commute
2.4%
Drive alone
1.5%
Carpool
78.6%
Public transit
7.3%
Work from home
24.8 min
Avg commute
Housing
$335,000$-41,000 vs state
Median home value
$1,098
Median rent
82.4%
Homeownership rate
10,499
Total housing units
94.3%
Occupied
5.7%
Vacant
17.6%
Renter-occupied
Social & access
91.4%
With health insurance
97.2%
With broadband internet
28.3%
Foreign-born
5.6%
Veterans (18+)
10.8%
With a disability
88.9%
Speak language other than English at home
Education
93.3%
High School+
27.2%
Bachelor's+
Largest cities in Idaho
Other counties in Idaho
Part of Idaho
Metro areas in Idaho
County rankings
Frequently Asked Questions
Jefferson County, Idaho has a population of 32,234 according to the US Census Bureau's 2023 American Community Survey 5-year estimates, making it the 12th-largest county in Idaho. Population density is 29 people per square mile.
The population of Jefferson County has grown 32.9% since 2010 (26,222 → 34,854), a +2.05% annualized rate.
The median household income in Jefferson County, Idaho is $82,952, with mean (average) household income of $95,822 and per-capita income of $30,733. 7.4% of residents live below the federal poverty level.
In Jefferson County, the largest racial and ethnic groups are White (88.3%), Hispanic or Latino (2.4%), Black or African American (0.1%). Figures are from the US Census Bureau's 2023 ACS 5-year estimates and reflect self-reported responses.
The median age in Jefferson County, Idaho is 32.3 years. Residents are 48.7% female and 51.3% male.
The median home value in Jefferson County is $335,000 and median monthly rent is $1,098. 82.4% of occupied housing units are owner-occupied. The county has 10,499 total housing units, 5.7% of which are vacant.
The largest employment sector in Jefferson County, Idaho is professional, scientific, and management services, employing 24.0% of workers. The unemployment rate is 1.6%.
Boise City is among the largest cities associated with Jefferson County, Idaho, with a population of 235,701.
Jefferson County, ID Climate
Jefferson County, ID has an average annual temperature of 6.1°C (43°F) and receives about 249 mm of precipitation per year. The warmest month is July and the coldest is January. Figures are 1970–2000 climate normals.
6.1°C
Avg Temp
249
Precip (mm/yr)
Jul
Hottest Month
Jan
Coldest Month
| Month | Avg (°C/°F) | Precip |
|---|---|---|
| January | -8° / 17° | 18 mm |
| February | -5° / 24° | 16 mm |
| March | 1° / 34° | 16 mm |
| April | 6° / 43° | 20 mm |
| May | 11° / 52° | 34 mm |
| June | 16° / 60° | 32 mm |
| July | 20° / 67° | 18 mm |
| August | 19° / 66° | 18 mm |
| September | 14° / 57° | 19 mm |
| October | 7° / 45° | 17 mm |
| November | -1° / 31° | 21 mm |
| December | -7° / 19° | 20 mm |
1970–2000 normals from WorldClim 2.1 (~9 km grid). Precipitation can be less precise near mountains or coastlines, where rainfall varies sharply over short distances.
Best time to visit Jefferson County, ID
The most comfortable months to visit Jefferson County, ID are typically July, August and June, when temperatures are mildest and rainfall is relatively low. The hottest month is July (around 30°C high). The coldest is January (near -14°C low). May is usually the wettest month.
Where to stay near Jefferson County
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Statewide data for Idaho
Population, race, income, age, and trends across Idaho
Data from the American Community Survey (ACS) 5-Year estimates.
Source: U.S. Census Bureau ACS, 2026.