Jefferson County's 2026 population is estimated at 36,182, reflecting a 0.1% growth rate over the past year (World Population Review estimate based on U.S. Census Bureau data). Jefferson County is the 38th largest county in Illinois. The 2010 population was 38,757 and has grown -6.64% since 2010.
Overall: 41.2 years
Female: 43.5 years
Male: 39.2 years
There are 28,410 adults, (7,298 of whom are seniors) in Jefferson County.
Female: 17,679 (48.4%)
Male: 18,871 (51.6%)
The racial composition of Jefferson County includes 83.96% White, 6.22% Black or African American, and smaller percentages for Asian, other race, Native American and multiracial populations.
| Race | Population ↓ | Percentage (of total) |
|---|---|---|
| White | 30,687 | 83.96% |
| Two or more races | 2,776 | 7.6% |
| Black or African American | 2,272 | 6.22% |
| Asian | 376 | 1.03% |
| Other race | 317 | 0.87% |
| Native American | 122 | 0.33% |
Jefferson County 's average per capita income is $43,701. Household income levels show a median of $63,118. The poverty rate stands at 13.53%.
| Name | Median ↓ | Mean |
|---|---|---|
| Married Families | $94,387 | $111,261 |
| Families | $78,998 | $96,235 |
| Households | $63,118 | $80,324 |
| Non Families | $37,721 | $48,369 |
Average Income
Median Household Income
Poverty Rate