O'Brien County's 2026 population is estimated at 14,646, reflecting a 1.34% growth rate over the past year (World Population Review estimate based on U.S. Census Bureau data). O'Brien County is the 52nd largest county in Iowa. The 2010 population was 14,405 and has grown 1.67% since 2010.
Data after 2023 is projected based on recent change
Overall: 39.5 years
Female: 40.6 years
Male: 38.4 years
There are 10,680 adults, (2,989 of whom are seniors) in O'Brien County.
Female: 7,070 (50%)
Male: 7,056 (50%)
The racial composition of O'Brien County includes 87.48% White, 3.45% other race, and smaller percentages for Black or African American, Asian, Native American, Native Hawaiian or Pacific Islander and multiracial populations.
| Race | Population ↓ | Percentage (of total) |
|---|---|---|
| White | 12,358 | 87.48% |
| Two or more races | 872 | 6.17% |
| Other race | 487 | 3.45% |
| Black or African American | 240 | 1.7% |
| Asian | 92 | 0.65% |
| Native American | 55 | 0.39% |
| Native Hawaiian or Pacific Islander | 22 | 0.16% |
O'Brien County 's average per capita income is $46,924. Household income levels show a median of $68,356. The poverty rate stands at 13.32%.
| Name | Median ↓ | Mean |
|---|---|---|
| Married Families | $99,152 | - |
| Families | $96,077 | $102,052 |
| Households | $68,356 | $84,439 |
| Non Families | $43,611 | $49,758 |
Average Income
Median Household Income
Poverty Rate
