Belknap, Illinois Demographics & Population 2026

A note before these figures: with a population of 115, Belknap'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

Belknap is a small community located in Illinois, within Johnson County. The total population is 115. It ranks as the 1318th most populous out of 1,445 Census-designated places in Illinois.

Age Demographics

The median age in Belknap is 50.5 years. This is 29% higher than the state median of 39.0 years. Only 8.7% of residents are under 18, indicating fewer families with children.

Economy, Income & Housing

The median household income in Belknap is $67,500. This is 19% lower than the state median of $83,390. It is also 16% lower than the national median of $80,734. The poverty rate stands at 6.1%. This is 48% lower than the state poverty rate of 11.8%. The survey records no unemployed residents in Belknap, which reflects the size of the sample rather than a labor market without joblessness. The median home value is $40,700. Housing costs are 85% lower than the state median of $263,300. With a home-value-to-income ratio of just 0.6x, Belknap is one of the most affordable housing markets in the area. 72.9% of occupied housing units are owner-occupied. This homeownership rate is 9% higher than the state average of 67.1%.

Race & Ethnicity

Belknap has a predominantly White (non-Hispanic) population, comprising 96.5% of all residents. The White (non-Hispanic) population is significantly higher than the state average (96.5% vs 58.1%).

Education

24.5% of residents aged 25 and older hold a bachelor's degree or higher. This is 35% 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 91.2%.

Data Sources & Methodology

All demographic data for Belknap, 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.