Seneca, McHenry County, IL demographics:
population, income, and more

Total population
8,245
-0.9% year-over-year change
Median household income
$98,451/yr
4.5% year-over-year change
Housing units
3,347
1.7% year-over-year change

Seneca population

How many people live in Seneca

Seneca is home to 8,245 residents, according to the most recent Census data. Gender-wise, 50.4% of Seneca locals are male, and 49.6% are female.

Total population
8,245
-0.9% year-over-year change
Gender ratio
Male
50.4%
4,160
Female
49.6%
4,085
Value Percent YoY change
Male 4,160 50.4% 0.6%
Female 4,085 49.6% -2.4%
A higher population often means more rental variety and livelier areas. The gender balance—how many men live here compared to women—can reveal a lot about the community and the lifestyles of its residents. Use this info to get a sense of the area's pace and personality.

Age demographics

The median age in Seneca is 40, with the population distributed as follows: about 15.6% are children under 15, then 14.2% are in the 15 to 24 age group. Adults between 25 and 44 make up 24.5% of the population, while another 27.6% fall into the 45 to 64 bracket. Finally, around 18.1% are 65 or older.

Median age
39.7
Age breakdown
Under 15
15.6%
15 to 24
14.2%
25 to 44
24.5%
45 to 64
27.6%
Over 65
18.1%
Value Percent YoY change
Under 15 1,283 15.6% -14.4%
15 to 24 1,168 14.2% 4.9%
25 to 44 2,020 24.5% -2.3%
45 to 64 2,278 27.6% 4.6%
Over 65 1,495 18.1% 2.3%
The age composition helps you get insight into who lives in the area. A younger population might mean a more active, fast-paced vibe, while an older one could suggest a quieter, slower lifestyle. If there's a balanced makeup, you’re likely to find a variety of services, housing types, and community spaces that cater to different life stages.

Racial makeup

In Seneca, 87.7% of the population are US-born citizens, while 5% have gained naturalized citizenship. At the same time, 7.4% of residents are non-citizens. As for race, 76% of locals are Caucasian, 1.9% are African American and 2% have Asian roots. There’s also a share of 14.5% that includes residents with two or more races.

Citizenship
U.S.-born citizens
87.7%
Non-U.S.-born citizens
5%
Non-citizens
7.4%
Value Percent YoY change
U.S.-born citizens 7,230 87.7% -2.6%
Non-U.S.-born citizens 408 5% 10.3%
Non-citizens 606 7.4% 15.4%
Racial breakdown
White
76%
Black or African American
1.9%
American Indian and Alaska Native
1.1%
Asian
2%
Native Hawaiian and other Pacific Islander
0%
Two or more races
14.5%
Other
4.6%
Value Percent
White 6,264 76%
Black or African American 153 1.9%
American Indian and Alaska Native 92 1.1%
Asian 161 2%
Native Hawaiian and other Pacific Islander 3 0%
Two or more races 1,196 14.5%
Other 375 4.6%

Households in Seneca

A peek inside Seneca households

Seneca has 3,240 households, with an average of 3 members in each. Of these, 67.2% are families, while the remaining 32.8% are made up of individuals living alone or with non-relatives, such as roommates.

Households stats

Total households
3,240
2.2% year-over-year change
Average people per household
3
Non-family households
1,063
Family households
2,177
Value Percent YoY change
Non-family households 1,063 32.8% 9.6%
Family households 2,177 67.2% -1.0%
The mix between family and non-family households gives a glimpse into daily life. A higher percentage of families might mean more parks and schools, while more non-family setups can mean flexible housing and diverse living styles. For renters, this can signal what kinds of homes are common and can help you figure out if the area matches your lifestyle.

Housing in Seneca

The housing landscape of Seneca

Seneca's housing consists of 3,347 units, with 69.2% being detached single-family homes ideal for those wanting space. Attached options, including duplexes and townhouses, make up 10.6% and offer a more compact, shared living style. Then there are the multifamily buildings in the area, and for those seeking flexibility, non-traditional options like mobile homes account for 0.8% of the housing landscape.

Housing units
3,347
1.7% year-over-year change
Housing types
Value Percent
1 unit, detached 2,316 69.2%
1 unit, attached 355 10.6%
2 units 69 2.1%
3 or 4 units 159 4.8%
5 to 9 units 223 6.7%
10 to 19 units 72 2.2%
20 to 49 units 68 2%
50 or more units 62 1.8%
Mobile home 25 0.8%
Homes built since 2020
28
64.7% year-over-year change

The age of buildings in Seneca

In Seneca, the median construction year is 1979. About 16.4% of homes were built before the 1940s, with another 2.6% going up by 1949. Most development happened in the second half of the 20th century. Then, 20.3% of homes were added from 2000 to 2009, 5.6% between 2010 and 2019, and 0.8% are part of the newest wave of development.

Construction year breakdown by decade
Value Percent YoY change
Built in 1939 or earlier 550 16.4% 4.8%
Built between 1940 and 1949 86 2.6% 38.7%
Built between 1950 and 1959 259 7.7% 0.4%
Built between 1960 and 1969 223 6.7% -10.4%
Built between 1970 and 1979 369 11% -3.1%
Built between 1980 and 1989 462 13.8% -5.3%
Built between 1990 and 1999 506 15.1% -0.8%
Built between 2000 and 2009 678 20.3% 2.4%
Built between 2010 and 2019 186 5.6% 32.9%
Built in 2020 or later 28 0.8% 64.7%
As a renter, knowing when homes were built helps you understand the potential condition and design of rental units. Newer builds may have more contemporary layouts, while older homes can offer character or larger lots, depending on the area.

Seneca occupancy rates

Out of the 3,240 occupied housing units in Seneca, 76.2% are owner-occupied, while 23.8% are lived in by tenants. Meanwhile, 3.2% of all homes on the local market sit vacant.

Occupied housing units
3,240
2.2% year-over-year change
Occupancy breakdown
Renter occupied
770
Owner occupied
2,470
Value Percent YoY
change
Renter occupied 770 23.8% -4.1%
Owner occupied 2,470 76.2% 4.3%
Unoccupied housing units
3.2%
Unoccupied housing units refer to homes that are currently without residents—whether they're waiting for renters or owners, used seasonally, or simply unclaimed. A higher share of empty homes may mean more housing availability, while a low number can reflect a tighter market with more competition. This, along with the renter-vs.-owner mix, helps paint a clearer picture of what types of housing and services are likely to be available in the area.

Seneca housing costs

Housing costs in Seneca come to a median of $1,433 per month, while tenants specifically pay a median gross rent of $1,215.

Median housing costs per month
$1,433/month
This figure sums up typical monthly housing costs for all households in the area. If you own, it includes mortgage payments in addition to property taxes, insurance and HOA fees. If you rent, it accounts for rent plus extras like utilities. It’s useful for seeing how local living expenses stack up compared to other places.
Median gross rent in Seneca
$1,215/month
Gross rent gives a more complete look at what renters actually pay, including not just base rent, but also utilities and fees. It’s a key number for evaluating rental affordability in your area of interest and understanding how it compares to nearby locations.

Education in Seneca

Seneca education at a glance

About 35% of the population in Seneca went to high school, while 23.7% pursued college studies. Another 9.3% earned an associate degree and 18.9% hold a bachelor’s. Meanwhile, 9.1% went even further, earning a master’s or doctorate.

Education level
Value Percent YoY change
No high school 263 4% 15.9%
High school diploma 2,315 35% 6.5%
College diploma 1,570 23.7% 0.3%
Associate degree 613 9.3% 7.0%
Bachelor's degree 1,253 18.9% 0.3%
Graduate degree 600 9.1% -10.8%
A community’s education mix can offer insights into the local economy and housing market. Higher levels of education often align with more job opportunities and stable incomes, which can increase demand for homes and influence both rent prices and rental availability.

Income in Seneca

How much people earn in Seneca

The average annual household income in Seneca was $116,089 in 2024, the most recent annual data available, according to the U.S. Census Bureau. This marked a +0.8% change from the previous year. At the same time, the median income stood at $98,451, reflecting a +4.5% shift over the same period.

Average household income in Seneca
$116,089/year
0.8% year-over-year change
Median household income in Seneca
$98,451/year
4.5% year-over-year change

Seneca income by age

In Seneca, households led by residents aged 25 to 44 — usually in the early to mid stages of their careers — have a median income of $111,310. Those with someone between 45 and 64 in charge, often well established professionally, earn $115,931 overall. Younger households, where the main provider is under 25 and just starting out, report a median income of $98,707, while those led by someone over 65, many of whom may be retired, have about $70,945 in earnings. Overall, 93.3% of the locals in this community live above the poverty line.

Income breakdown by age
Value YoY change
Under 25 $98,707 3.6%
25 - 44 $111,310 2.0%
45 - 64 $115,931 -10.9%
Over 65 $70,945 3.0%
Above poverty level
7,478
Below poverty level
536
Value Percent YoY
change
Above poverty level 7,478 93.3% 0.6%
Below poverty level 536 6.7% -9.8%

Employment in Seneca

Workforce and job types in Seneca

73.5% of the working population are employed in professional or administrative positions, while 26.5% are in hands-on or service-based jobs. Also, 10% run their own businesses, 70.2% are employed by private companies, and 13.8% work in the public sector.

Workforce demographics

White collar
3,247
Blue collar
1,171
Value Percent YoY change
White collar 3,247 73.5% -0.3%
Blue collar 1,171 26.5% 1.3%
Employer type
Self employees
10%
Private companies
70.2%
Governmental workers
13.8%
Not for profit companies
6.1%
Value Percent YoY change
Self employees 441 10% 12.2%
Private companies 3,100 70.2% -1.4%
Governmental workers 608 13.8% -1.8%
Not for profit companies 269 6.1% 4.7%

Transportation in Seneca

How people get around in Seneca

Commuting methods vary: 97% of residents travel by personal vehicle and 1.9% prefer to walk, while the remaining share relies on public transit or on two wheelers to get from A to B.

Means of transportation
Value Percent YoY change
Car 3,621 97% -1.5%
Taxicab 8 0.2% 14.3%
Bus or trolleybus 6 0.2% 20.0%
Railroad 23 0.6% 9.5%
Ferryboat 2 0% N/A
Motorcycle 3 0.1% 50.0%
Bicycle 1 0% -66.7%
Walk 71 1.9% 12.7%
Understanding how locals get to work can help you plan your own routine. High car usage might mean you’ll need a vehicle, while strong public transit or walkability could save you the hassle. Commute times also play a big role in quality of life—shorter trips can give you more time for the things you enjoy.

What is the median and average household income in Seneca by zipcode?

Zipcode Population Number of households Median income Average income
60098 33,130 13,168 $91,062 $115,457
60152 12,417 4,575 $98,451 $115,069
60180 1,831 704 $110,070 $120,058

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FAQs about Seneca demographics 

What is the total population of Seneca?

Seneca has a total population of 8,245 residents, according to the latest release from the U.S. Census Bureau: the 2019-2023 American Community Survey (ACS) 5-year estimates. This figure changed by -0.9% compared to a year ago.

What is the gender ratio in Seneca?

The gender ratio in Seneca is as follows:
  • 50.4% males (4,160 residents)
  • 49.6% females (4,085 residents)

What is the median age in Seneca?

The median age in Seneca is 39.7.

What is the age distribution of the population in Seneca?

The age distribution in Seneca is as follows:
  • Under 15: 15.6% (1,283 residents)
  • Ages 15-24: 14.2% (1,168 residents)
  • Ages 25-44: 24.5% (2,020 residents)
  • Ages 45-64: 27.6% (2,278 residents)
  • Over 65: 18.1% (1,495 residents)

What is the racial and ethnic makeup of Seneca?

The racial and ethnic makeup of Seneca is as follows:
  • White: 76% (6,264 residents)
  • Black or African American: 1.9% (153 residents)
  • American Indian and Alaska Native: 1.1% (92 residents)
  • Asian: 2% (161 residents)
  • Native Hawaiian and Other Pacific Islander: 0% (3 residents)
  • Two or More Races: 14.5% (1,196 residents)
  • Other: 4.6% (375 residents)

What percentage of the population in Seneca are U.S.-born citizens?

U.S.-born citizens represent 87.7% of the population in Seneca.

How many housing units are there in Seneca?

There are 3,347 housing units in Seneca, reflecting a +1.7% change compared to the previous year, according to the latest data from the U.S. Census Bureau.

How many households are in Seneca and what is the average household size?

Seneca has a total of 3,240 households, with an average of 3 people in each.

What is the median household income in Seneca?

Seneca has a median household income of $98,451, representing a +4.5% shift from the previous year, according to the U.S. Census Bureau.

What is the job market overview for Seneca?

Here’s a detailed breakdown of the local job market:

Job types:
  • White-collar workers: 73.5% (3,247 residents)
  • Blue-collar workers: 26.5% (1,171 residents)

Places of employment:
  • Self-employed: 10% (441 residents)
  • Private companies: 70.2% (3,100 residents)
  • Governmental workers: 13.8% (608 residents)
  • Not-for-profit companies: 6.1% (269 residents)

Data source & methodology

The demographic data on this page was sourced from the latest U.S. Census Bureau release—the 2019–2023 American Community Survey (ACS) 5-year estimates.

The information, issued annually, is compiled and published by the Point2Homes Research Team as soon as new data becomes available.

No representation, guarantee, or warranty is made concerning the accuracy or completeness of modified or aggregated information for particular areas.

Page last updated: September 2025