Marion is a city located in Williamson County, Illinois. Marion has a 2025 population of 17,068. It is also the county seat of Williamson County. Marion is currently growing at a rate of 0.28% annually and its population has increased by 1.41% since the most recent census, which recorded a population of 16,831 in 2020.
The average household income in Marion is $78,411 with a poverty rate of 15.97%. The median age in Marion is 40.4 years: 39.5 years for males, and 41.3 years for females.
Data after 2023 is projected based on recent change
The racial composition of Marion includes 86.22% White, 5.23% Black or African American, 3.14% Asian, and smaller percentages for other race, Native American and multiracial populations.
White (86.2%)
Black or African American (5.2%)
Two or more races (5.0%)
Asian (3.1%)
Other race (0.2%)
Native American (0.2%)
Race  | Population  | Percentage (of total)  | 
|---|---|---|
| White | 14,482 | 86.22% | 
| Black or African American | 879 | 5.23% | 
| Two or more races | 846 | 5.04% | 
| Asian | 527 | 3.14% | 
| Other race | 33 | 0.2% | 
| Native American | 29 | 0.17% | 
Married
Widowed
Divorced
Separated
Never Married
Marion's average per capita income is $47,616. Household income levels show a median of $57,281. The poverty rate stands at 15.97%.
Name  | Median  | Mean  | 
|---|---|---|
| Married Families | $106,392 | - | 
| Families | $78,851 | $100,593 | 
| Households | $57,281 | $78,411 | 
| Non Families | $33,900 | $50,209 | 
Average Income
Median Household Income
Poverty Rate