Seneca, Illinois Demographics & Population 2026
During the 2020–2024 ACS period, Seneca, Illinois had a total population of 2,450, the 465th largest village in Illinois, with a median household income of $86,830, which is 4% higher than the state average. The poverty rate is 22.2%.
Data vintage: U.S. Census Bureau ACS 2020–2024 5-Year Estimates · refreshed July 2026 · Methodology & source notes
Seneca Quick Facts
How Seneca Changed
Change from the 2019–2023 ACS period to 2020–2024. These are rolling five-year estimates, not year-over-year measurements.
| Metric | 2019–2023 | 2020–2024 | Change |
|---|---|---|---|
| Population | 2,525 | 2,450 | -3.0% |
| Median household income | $91,065 | $86,830 | -4.7% |
| Median home value | $206,400 | $227,500 | +10.2% |
How Seneca Compares
Median Household Income
Median Home Value
Economy & Housing
Household Income Distribution
Detailed income brackets
Employment
Housing Overview
People & Demographics
Age Distribution
Race & Ethnicity
Diversity Index
A less diverse community where one racial or ethnic group represents a large majority.
State average: 61 | National average: 61
Education
Educational Attainment (Adults 25+)
Seneca Rankings in Illinois
Explore Illinois Rankings
Other Cities in LaSalle County
| City | Population | Median Income | Poverty | Home Value |
|---|---|---|---|---|
| Ottawa | 18,447 | $71,413 | 17.3% | $154,000 |
| Streator | 12,330 | $57,609 | 20.3% | $94,700 |
| Peru | 9,775 | $74,808 | 9.0% | $154,300 |
| LaSalle | 9,498 | $57,732 | 18.8% | $113,500 |
| Mendota | 6,994 | $51,632 | 14.1% | $134,100 |
| Lake Holiday | 5,641 | $107,875 | 2.9% | $256,400 |
| Marseilles | 4,279 | $58,217 | 21.5% | $142,500 |
| Oglesby | 3,570 | $76,189 | 9.6% | $139,700 |
| Sheridan | 2,519 | $85,250 | 10.9% | $186,400 |
| Earlville | 1,942 | $63,553 | 16.5% | $142,200 |
Cities Similar to Seneca
These cities in the same state have comparable population and economic profiles.
| City | Population | Median Income | Home Value | Bachelor's+ | Poverty |
|---|---|---|---|---|---|
| Sheridan | 2,519 | $85,250 | $186,400 | 4.9% | 10.9% |
| Hinckley | 2,331 | $86,823 | $291,700 | 32.1% | 10.0% |
| Elmwood | 2,327 | $90,285 | $153,500 | 37.9% | 10.1% |
| Tremont | 2,366 | $79,810 | $187,400 | 32.9% | 5.1% |
| Marquette Heights | 2,492 | $75,625 | $123,800 | 25.2% | 3.7% |
Population Overview
Seneca is a small community located in Illinois, within LaSalle County. The total population is 2,450. It ranks as the 465th most populous out of 1,445 Census-designated places in Illinois.
Age Demographics
The median age in Seneca is 35.5 years. This is 9% lower than the state median of 39.0 years. With 28.6% of the population under 18, Seneca has a notably young demographic profile, suggesting a family-oriented community.
Economy, Income & Housing
The median household income in Seneca is $86,830. This is 4% higher than the state median of $83,390. It is also 8% higher than the national median of $80,734. The poverty rate stands at 22.2%. This is 88% 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 4.0%. This is 32% lower than the state rate of 5.8%. The median home value is $227,500. Housing costs are 14% lower than the state median of $263,300. With a home-value-to-income ratio of just 2.6x, Seneca is one of the most affordable housing markets in the area. 81.3% of occupied housing units are owner-occupied. This homeownership rate is 21% higher than the state average of 67.1%.
Race & Ethnicity
Seneca has a predominantly White (non-Hispanic) population, comprising 86.6% of all residents. Hispanic or Latino residents account for 10.0%. The Black or African American population (0.9%) is well below the state average of 13.3%.
Education
14.9% of residents aged 25 and older hold a bachelor's degree or higher. This is 61% 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 93.9%.
Data Sources & Methodology
All demographic data for Seneca, 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.
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Frequently Asked Questions
What is the population of Seneca, Illinois?
Seneca, Illinois has a population of 2,450 according to the most recent U.S. Census ACS 5-Year Estimates.
What is the median household income in Seneca, IL?
The median household income in Seneca is $86,830, which is 8% higher than the national median of $80,734.
What is the poverty rate in Seneca, IL?
The poverty rate in Seneca is 22.2%. This means approximately 543 residents live below the federal poverty line.
What is the racial makeup of Seneca, Illinois?
Seneca's population is 86.6% White, 0.9% Black, 10.0% Hispanic/Latino, and 0.0% Asian.
What is the median home value in Seneca, IL?
The median home value in Seneca is $227,500. The home-value-to-income ratio is 2.6x.
How educated is Seneca, Illinois?
14.9% of adults (25+) in Seneca hold a bachelor's degree or higher, and 2.8% hold a graduate or professional degree.