Demographics of Jefferson County, Idaho

Jefferson County, Idaho had 35,297 people on July 1, 2025, by the Census Bureau’s estimate: +4,217 since July 2020. Age, income, poverty, housing and origin below come from the American Community Survey, averaged over 2020–2024, each with its margin of error.

Jefferson County, in four figures

35,297
Population: July 1, 2025, Vintage 2025 estimate.; +13.6%
Change since July 2020: +4,217 people.; 32.8 ±0.4
Median age: ACS 2020–⁠2024.; $86,679 ±$3,818
Median household income: ACS 2020–⁠2024, in 2024 dollars.

Population, year by year

July 1 estimates from the Census Bureau’s Vintage 2025. Each year's change is births less deaths, net moves from abroad and net moves from elsewhere in the country, with the Bureau's small residual. The 2020 row's components run 3 months, from the April census to July 1.

Jefferson County, Idaho's population grew 13.6% from July 2020 to July 2025, against +3.1% nationally

The July 1 estimate of Jefferson County, Idaho's resident population and the nation's, each year of the Census Bureau's Vintage 2025, as a share of its July 2020 level (= 100).

U.S. Census Bureau — Census Bureau population estimates — counties and Puerto Rico municipios, with components of change

About this chart

The figures

Jefferson County, Idaho's population grew 13.6% from July 2020 to July 2025, against +3.1% nationally. The July 1 estimate of Jefferson County, Idaho's resident population and the nation's, each year of the Census Bureau's Vintage 2025, as a share of its July 2020 level (= 100).
July 1	Population	Index	United States
2020	31,080	100.0	100.0
2021	32,207	103.6	100.2
2022	33,358	107.3	100.7
2023	34,296	110.3	101.6
2024	34,856	112.1	102.5
2025	35,297	113.6	103.1

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Population of Jefferson County, Idaho on July 1 of each year, Vintage 2025
July 1	Population	Change	Births less deaths	From abroad	From elsewhere in the country
2020	31,080	+189	+77	+1	+110
2021	32,207	+1,127	+190	+5	+958
2022	33,358	+1,151	+177	+56	+887
2023	34,296	+938	+241	+90	+603
2024	34,856	+560	+209	+80	+278
2025	35,297	+441	+212	+4	+224

Age, 2020–2024

The median age is 32.8 ±0.4: for men 32.6 ±0.3 and for women 33.2 ±0.8. Shares are of everyone the survey counts, in the Bureau’s sex-by-age table (B01001).

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People in Jefferson County by age, ACS 2020–2024
Age	People	Share	Idaho	United States
Under 5	2,369 ±13	7.1% ±<0.1	5.9% ±<0.1	5.6% ±<0.1
5 to 17	8,355 ±394	25.2% ±1.2	18.2% ±0.2	16.3% ±<0.1
18 to 24	2,892 ±281	8.7% ±0.8	9.8% ±0.1	9.1% ±<0.1
25 to 44	8,488 ±429	25.6% ±1.3	26.1% ±0.2	26.9% ±<0.1
45 to 64	7,096 ±340	21.4% ±1.0	23.0% ±0.2	24.8% ±<0.1
65 and over	3,954 ±332	11.9% ±1.0	17.0% ±0.2	17.2% ±<0.1

Income and poverty, 2020–2024

Median household income is $86,679 ±$3,818, and income per person $31,834 ±$1,703, in 2024 dollars. The median is $77,800 ±$743 in Idaho and $80,734 ±$166 in the United States.

Households by income

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Households in Jefferson County by income, ACS 2020–2024
Household income	Households	Share	Idaho	United States
Under $25,000	1,053 ±220	10.3% ±2.1	12.5% ±0.3	14.6% ±<0.1
$25,000 to $49,999	1,467 ±332	14.4% ±3.2	17.6% ±0.4	16.7% ±<0.1
$50,000 to $74,999	1,677 ±263	16.4% ±2.6	18.1% ±0.4	15.5% ±<0.1
$75,000 to $99,999	2,019 ±277	19.8% ±2.7	14.7% ±0.4	12.6% ±<0.1
$100,000 to $149,999	2,207 ±297	21.6% ±2.9	19.3% ±0.4	17.5% ±<0.1
$150,000 to $199,999	938 ±193	9.2% ±1.9	8.7% ±0.3	9.6% ±<0.1
$200,000 or more	838 ±208	8.2% ±2.0	9.2% ±0.3	13.4% ±0.1

Poverty by age

The poverty rate is the share of people whose family income is below the federal threshold for their family’s size, of everyone for whom the Bureau determines it (B17020).

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Poverty rate in Jefferson County by age, ACS 2020–2024
Age	Below poverty	Rate	Idaho	United States
All ages	3,192 ±877	9.7% ±2.7	10.6% ±0.3	12.5% ±0.1
Under 18	1,320 ±330	12.3% ±3.0	12.4% ±0.5	16.1% ±0.1
18 to 59	1,344 ±469	8.1% ±2.8	10.4% ±0.3	11.6% ±0.1
60 and over	528 ±137	9.2% ±2.3	9.1% ±0.4	11.0% ±<0.1

Housing, 2020–2024

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Housing in Jefferson County, ACS 2020–2024
Measure	Jefferson County	Idaho	United States
Housing units	10,779 ±32	795,014 ±223	143,775,355 ±10,234
Occupied	94.6% ±1.7	89.7% ±0.3	89.9% ±0.1
Vacant	5.4% ±1.7	10.3% ±0.3	10.1% ±0.1
Owner occupied	83.0% ±2.4	72.1% ±0.4	65.2% ±0.3
Renter occupied	17.0% ±2.3	27.9% ±0.4	34.8% ±0.1
Median home value	$408,400 ±$21,935	$418,600 ±$2,550	$332,700 ±$236
Median gross rent	$1,138 ±$85	$1,238 ±$16	$1,413 ±$2
Median year built	1994 ±3	1991 ±1	1980 ±1

Occupied and vacant are shares of all housing units; owner and renter occupied are shares of occupied units. Value and rent are medians in 2024 dollars.

Origin and place of birth, 2020–2024

Hispanic or Latino origin is not a race in the Census Bureau’s tables. Here the people of Hispanic origin, of any race, are one row, and everyone else is counted by race alone (B03002), so the rows add to the whole.

Hispanic origin and race

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People in Jefferson County by Hispanic origin and race, ACS 2020–2024
Origin	People	Share	Idaho	United States
Hispanic or Latino	3,638 ±0	11.0% ±<0.1	13.6% ±<0.1	19.3% ±<0.1
White alone, not Hispanic	28,414 ±152	85.7% ±0.5	78.6% ±0.1	57.4% ±<0.1
Black alone, not Hispanic	0 to 43	0% to 0.1%	0.7% ±<0.1	11.9% ±<0.1
Asian alone, not Hispanic	6 to 78	< 0.1% to 0.2%	1.3% ±<0.1	5.9% ±<0.1
American Indian and Alaska Native alone, not Hispanic	0 to 129	0% to 0.4%	0.7% ±<0.1	0.5% ±<0.1
Native Hawaiian and Other Pacific Islander alone, not Hispanic	0 to 12	0% to < 0.1%	0.1% ±<0.1	0.2% ±<0.1
Some other race alone, not Hispanic	0 to 260	0% to 0.8%	0.6% ±0.1	0.6% ±<0.1
Two or more races, not Hispanic	855 ±94	2.6% ±0.3	4.2% ±0.1	4.3% ±<0.1

A range (the estimate less and plus its margin) where the Bureau's estimate is too uncertain to state as one number: a coefficient of variation over 30%.

Place of birth and citizenship

“Born a citizen outside the states” counts people born in Puerto Rico, the island areas, or abroad to American parents. Naturalized citizens and those who are not citizens together make up the people born abroad (B05002).

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People in Jefferson County by place of birth and citizenship, ACS 2020–2024
Born	People	Share	Idaho	United States
Born in the state	21,921 ±799	66.1% ±2.4	43.9% ±0.3	57.3% ±<0.1
Born in another state	9,566 ±785	28.9% ±2.4	49.1% ±0.3	26.9% ±<0.1
Born a citizen outside the states	81 to 483	0.2% to 1.5%	1.0% ±0.1	1.7% ±<0.1
Born abroad	1,385 ±231	4.2% ±0.7	5.9% ±0.2	14.1% ±<0.1
Naturalized citizens	618 ±168	1.9% ±0.5	2.7% ±0.1	7.4% ±<0.1
Not citizens	767 ±168	2.3% ±0.5	3.2% ±0.2	6.8% ±<0.1

A range (the estimate less and plus its margin) where the Bureau's estimate is too uncertain to state as one number: a coefficient of variation over 30%.

Jefferson County among the counties of Idaho

12th of 44 by population, July 2025. Every one is listed on the Idaho page.

Counties of Idaho near Jefferson County in population, July 2025
County	July 2025	Change since 2020
Madison County	55,172	+4.2%
Bonner County	54,420	+14.8%
Bingham County	51,153	+6.4%
Nez Perce County	42,905	+1.8%
Latah County	41,842	+5.6%
Jefferson County	35,297	+13.6%
Elmore County	29,465	+2.8%
Payette County	27,824	+8.8%
Cassia County	26,397	+6.6%
Jerome County	26,362	+8.6%
Blaine County	25,517	+4.8%

Elsewhere on the site

Sources

Census Bureau population estimates — counties and Puerto Rico municipios, with components of change — U.S. Census Bureau · U.S. Government work · retrieved September 25, 2026
American Community Survey 5-year estimates — table-based Summary File · U.S. Government work

Data retrieved September 25, 2026