South Wilmington, Illinois Demographics & Population 2026

A note before these figures: with a population of 600, South Wilmington'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

South Wilmington is a small community located in Illinois, within Grundy County. The total population is 600. It ranks as the 874th most populous out of 1,445 Census-designated places in Illinois.

Age Demographics

The median age in South Wilmington is 43.0 years. This is 10% higher than the state median of 39.0 years. 11.7% 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 South Wilmington is $86,750. This is 4% higher than the state median of $83,390. It is also 7% higher than the national median of $80,734. The poverty rate stands at 5.7%. This is 52% lower than the state poverty rate of 11.8%. The unemployment rate is 4.1%. This is 30% lower than the state rate of 5.8%. The median home value is $174,400. Housing costs are 34% lower than the state median of $263,300. With a home-value-to-income ratio of just 2.0x, South Wilmington is one of the most affordable housing markets in the area. 90.0% of occupied housing units are owner-occupied. This homeownership rate is 34% higher than the state average of 67.1%.

Race & Ethnicity

South Wilmington has a predominantly White (non-Hispanic) population, comprising 94.7% of all residents. Hispanic or Latino residents account for 3.8%. The White (non-Hispanic) population is significantly higher than the state average (94.7% vs 58.1%). The Hispanic or Latino population (3.8%) is well below the state average of 18.8%. The Asian population (0.7%) is well below the state average of 5.9%.

Education

13.1% of residents aged 25 and older hold a bachelor's degree or higher. This is 66% lower than the state rate of 37.9%. Nationally, 35.7% of adults hold at least a bachelor's degree. The high school graduation rate (or equivalent) is 91.1%.

Data Sources & Methodology

All demographic data for South Wilmington, 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.