Mill Creek, Illinois Demographics & Population 2026

A note before these figures: with a population of 37, Mill Creek's ACS estimates come from a small number of survey responses and carry wide margins of error. Individual percentages below — particularly rates that round to 0% or 100% — are approximations, not precise measurements. See data.census.gov for the published margins of error.

Population Overview

Mill Creek is a small community located in Illinois, within Union County. The total population is 37. It ranks as the 1418th most populous out of 1,445 Census-designated places in Illinois.

Age Demographics

The median age in Mill Creek is 57.8 years. This is 48% higher than the state median of 39.0 years. Only 8.1% of residents are under 18, indicating fewer families with children. 16.2% of residents are 75 or older, suggesting a significant retirement-age population with implications for healthcare services and senior housing.

Economy, Income & Housing

The median household income in Mill Creek is $151,250. This is 81% higher than the state median of $83,390. It is also 87% higher than the national median of $80,734. The poverty rate stands at 29.7%. This is 152% higher than the state poverty rate of 11.8%. With more than one in five residents living below the poverty line, economic hardship is a significant challenge for the community. The unemployment rate is 31.6%. This is 441% higher than the state rate of 5.8%. 100.0% of occupied housing units are owner-occupied. This homeownership rate is 49% higher than the state average of 67.1%.

Race & Ethnicity

Mill Creek has a predominantly White (non-Hispanic) population, comprising 89.2% of all residents. The White (non-Hispanic) population is significantly higher than the state average (89.2% vs 58.1%).

Education

20.0% of residents aged 25 and older hold a bachelor's degree or higher. This is 47% lower than the state rate of 37.9%. Nationally, 35.7% of adults hold at least a bachelor's degree. No surveyed resident aged 25 or older reported leaving school before earning a high school diploma, though a rate of exactly 100% reflects the limits of a small sample.

Data Sources & Methodology

All demographic data for Mill Creek, Illinois is sourced from the U.S. Census Bureau's American Community Survey (ACS) 2020–2024 5-Year Estimates. The ACS collects data from approximately 3.5 million households annually and pools five years of responses so that even small communities can be measured, though the margin of error widens as the population falls. Comparisons are made against Illinois state averages and national averages calculated from the same dataset. Rankings reflect the city's position among all 1,445 Census-designated places in Illinois. Read more about how these figures are produced on our methodology page, or visit data.census.gov for official data.