Jefferson County's 2026 population is estimated at 36,044, reflecting a 1.68% growth rate over the past year (World Population Review estimate based on U.S. Census Bureau data). Jefferson County is the 12th largest county in Idaho. The 2010 population was 26,222 and has grown 37.46% since 2010.
Data after 2023 is projected based on recent change
Overall: 32.8 years
Female: 33.2 years
Male: 32.6 years
There are 22,430 adults, (3,954 of whom are seniors) in Jefferson County.
Female: 16,188 (48.8%)
Male: 16,966 (51.2%)
The racial composition of Jefferson County includes 87.53% White, 3.85% other race, and smaller percentages for Native American, Black or African American, Asian, Native Hawaiian or Pacific Islander and multiracial populations.
| Race | Population ↓ | Percentage (of total) |
|---|---|---|
| White | 29,020 | 87.53% |
| Two or more races | 2,686 | 8.1% |
| Other race | 1,278 | 3.85% |
| Native American | 79 | 0.24% |
| Black or African American | 45 | 0.14% |
| Asian | 42 | 0.13% |
| Native Hawaiian or Pacific Islander | 4 | 0.01% |
Jefferson County 's average per capita income is $47,578. Household income levels show a median of $86,679. The poverty rate stands at 9.68%.
| Name | Median ↓ | Mean |
|---|---|---|
| Married Families | $97,875 | - |
| Families | $92,015 | $108,437 |
| Households | $86,679 | $99,354 |
| Non Families | $32,612 | $46,062 |
Average Income
Median Household Income
Poverty Rate
