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Marion, IL Profile: Facts & Data

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Marion, Illinois - Basic Facts

The City of Marion had a population of 16,585 as of July 1, 2025.

The primary coordinate point for Marion is located at latitude 37.7306 and longitude -88.9331 in Williamson County. The formal boundaries for the City of Marion encompass a land area of 16.24 sq. miles and a water area of 0.23 sq. miles. Williamson County is in the Central time zone (GMT -6).

The City of Marion has a C1 Census Class Code which indicates an active incorporated place that does not serve as a county subdivision equivalent. It also has a Functional Status Code of "A" which identifies an active government providing primary general-purpose functions.

The City of Marion is located within West Marion Election Precinct, a minor civil division (MCD) of Williamson County.


Jump to... (On This Page!)
  1. Marion 2025 Demographic Data
  2. Growth Rates for Marion (Historical & 5-Year Forecast)
  3. Peer Comparisons (Rank and Percentile)
  1. Neighborhoods Demographics (Home Values, Household Income, etc.)
  2. Illinois Research Tools (Easy Tools & Current Data)
  3. Illinois Data Comparison Tool - 2025 Demographics
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Marion, IL Data & Demographics (As of July 1, 2025)

POPULATION

Total Population 16,585 (100%)
Population in Households 16,121 (97.2%)
Population in Families 11,571 (69.8%)
Population in Group Quarters1 464 ( 2.8%)
Population Density 1,152
Diversity Index2 37
 
 

INCOME

Median Household Income $53,325
Average Household Income $71,401
% of Income for Mortgage4 19%
Per Capita Income $33,273
Wealth Index5 53
Socioeconomic Status Index6 Moderate (48.6)
 

HOUSING

Total HU (Housing Units) 8,922 (100%)
Owner Occupied HU 4,514 (50.6%)
Renter Occupied HU 3,208 (36.0%)
Vacant Housing Units 1,200 (13.4%)
Median Home Value $164,721
Average Home Value $221,375
Housing Affordability Index3 106
 

HOUSEHOLDS

Total Households 7,722
Average Household Size 2.09
Family Households 4,189
Average Family Size 3.00
NOTES
  1. Group Quarters - a place where people live or stay in a group living arrangement. Includes college residents halls, nursing facilities, military barracks, and correctional facilities.
  2. The Diversity Index is a scale of 0 to 100 that represents the likelihood that two persons, chosen at random from the same area, belong to different races or ethnic groups. If an area's entire population belongs to one race AND one ethnic group, then the area has zero diversity. An area's diversity index increases to 100 when the population is evenly divided into two or more race/ethnic groups.
  3. The Housing Affordability Index base is 100 and represents a balance point where a resident with a median household income can normally qualify to purchase a median price home. Values above 100 indicate increased affordability, while values below 100 indicate decreased affordability.
  4. The % of Income for Mortgage quantifies the percentage of median household income dedicated to mortgage payments on a home priced at the median value (assuming a 30-year mortgage and a 20% down payment).
  5. The Wealth Index is based on a number of indicators of affluence including average household income and average net worth, but it also includes the value of material possessions and resources. It represents the wealth of the area relative to the national level. Values above or below 100 represent above-average wealth or below-average wealth compared to the national level.
  6. The Socioeconomic Index ranges from zero (lowest relative status) to 100 (highest relative status). This measure quantifies disparities in social position of an area's inhabitants and is built from a broad range of demographic, housing, and socioeconomic inputs. More information on this measure can be found in Esri's SEI tutorial.

GROWTH RATE / YEAR

 2020-2025 2025-2030
Population -0.31% -0.11%
Households 0.44% 0.33%
Families   0.28%
Median Household Income   2.45%
Per Capita Income   1.94%
Owner Occupied HU   1.01%

Marion, IL - Peer Comparisons by Rank and Percentile

The table below compares Marion to the other 1,461 incorporated cities, towns and CDPs in Illinois by rank and percentile using July 1, 2025 data. The location Ranked # 1 has the highest value. A location that ranks higher than 75% of its peers would be in the 75th percentile of the peer group.

Variable Description Rank Percentile
Total Population # 150 90th
Population Density # 589 60th
Median Household Income # 1312 10th
Housing Affordability Index # 477 33rd
Per Capita Income # 1115 24th
Diversity Index # 424 71st

Additional comparisons and rankings can be made with a VERY EASY TO USE Illinois Census Data Comparison Tool.

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