Marshall County's 2026 population is estimated at 40,716, reflecting a 0.4% growth rate over the past year (World Population Review estimate based on U.S. Census Bureau data). Marshall County is the 15th largest county in Iowa. The 2010 population was 40,722 and has grown -0.01% since 2010.
Data after 2023 is projected based on recent change
Overall: 38.5 years
Female: 39.5 years
Male: 37.7 years
There are 29,939 adults, (7,301 of whom are seniors) in Marshall County.
Female: 19,785 (49.3%)
Male: 20,329 (50.7%)
The racial composition of Marshall County includes 70.62% White, 8.2% other race, 4.12% Asian, and smaller percentages for Black or African American, Native American and multiracial populations.
| Race | Population ↓ | Percentage (of total) |
|---|---|---|
| White | 28,330 | 70.62% |
| Two or more races | 5,513 | 13.74% |
| Other race | 3,289 | 8.2% |
| Asian | 1,652 | 4.12% |
| Black or African American | 824 | 2.05% |
| Native American | 506 | 1.26% |
Marshall County 's average per capita income is $44,300. Household income levels show a median of $73,315. The poverty rate stands at 11.15%.
| Name | Median ↓ | Mean |
|---|---|---|
| Married Families | $96,194 | $108,593 |
| Families | $87,339 | $99,260 |
| Households | $73,315 | $85,510 |
| Non Families | $44,072 | $56,765 |
Average Income
Median Household Income
Poverty Rate