Stephenson County's 2026 population is estimated at 42,570, reflecting a -0.6% growth rate over the past year (World Population Review estimate based on U.S. Census Bureau data). Stephenson County is the 33rd largest county in Illinois. The 2010 population was 47,606 and has grown -10.58% since 2010.
Data after 2023 is projected based on recent change
Overall: 45.3 years
Female: 47.3 years
Male: 43.2 years
There are 34,472 adults, (10,671 of whom are seniors) in Stephenson County.
Female: 22,364 (51.1%)
Male: 21,404 (48.9%)
The racial composition of Stephenson County includes 79.58% White, 8.63% Black or African American, and smaller percentages for other race, Asian, Native American, Native Hawaiian or Pacific Islander and multiracial populations.
| Race | Population ↓ | Percentage (of total) |
|---|---|---|
| White | 34,830 | 79.58% |
| Black or African American | 3,779 | 8.63% |
| Two or more races | 3,763 | 8.6% |
| Other race | 862 | 1.97% |
| Asian | 361 | 0.82% |
| Native American | 170 | 0.39% |
| Native Hawaiian or Pacific Islander | 3 | 0.01% |
Stephenson County 's average per capita income is $44,766. Household income levels show a median of $64,043. The poverty rate stands at 13.93%.
| Name | Median ↓ | Mean |
|---|---|---|
| Married Families | $95,907 | - |
| Families | $81,855 | $95,729 |
| Households | $64,043 | $79,920 |
| Non Families | $39,078 | $50,923 |
Average Income
Median Household Income
Poverty Rate
