Waterloo Flag

Waterloo

County:
Monroe County
County Seat:
Yes
Area (mi²):
8.234
State:
Illinois

Waterloo is a city located in Monroe County, Illinois. Waterloo has a 2026 population of 11,245. It is also the county seat of Monroe County. Waterloo is currently growing at a rate of 0.36% annually and its population has increased by 2.19% since the most recent census, which recorded a population of 11,004 in 2020.

The median household income in Waterloo is $98,711 with a poverty rate of 5.89%. The median age in Waterloo is 41.5 years: 39.8 years for males, and 43.1 years for females. For every 100 females there are 95.5 males.

11.2K
Total Population
1,366
Density (mi²)
40 0.36%
Growth

Waterloo Population

Waterloo Population

Data after 2023 is projected based on recent change

Year ↓
Population
Growth
Annual Change
202611,245400.36%
202511,205400.36%
202411,165-37-0.33%
202311,202520.47%
202211,150690.62%
202111,081680.62%
202011,0044394.16%
201910,5651171.12%
201810,448840.81%
201710,3641201.17%
201610,244810.8%
201510,163660.65%
201410,097-5-0.05%
201310,102410.41%
201210,061140.14%
201110,047770.77%
20109,9701591.62%
20007,6142,54250.12%
19905,0724269.17%
19804,6461002.2%
19704,54680721.58%
19603,73991832.54%
19502,82100%

Median Age

Overall: 41.5 years
Female: 43.1 years
Male: 39.8 years

Waterloo Adults

There are 8,691 adults, (2,293 of whom are seniors) in Waterloo.

Sex Ratio

Female: 5,693 (51.2%)
Male: 5,436 (48.8%)

Demographics

The racial composition of Waterloo includes 94.38% White, and smaller percentages for Two or more races, Asian, Black or African American, other race, Native American and multiracial populations.

Population by Race

Race
Population ↓
Percentage (of total)
White10,50394.38%
Two or more races2582.32%
Asian1891.7%
Black or African American1151.03%
Other race490.44%
Native American150.13%
Race
Population ↓
Percentage (of total)
Two or more races1181.06%
Other race490.44%
White330.3%
Race
Population ↓
Percentage (of total)
White10,47094.08%
Asian1891.7%
Two or more races1401.26%
Black or African American1151.03%
Native American150.13%

Waterloo Marital Status

Economics and Income Statistics

Waterloo 's average per capita income is $60,876. Household income levels show a median of $98,711. The poverty rate stands at 5.89%.

Families: A family includes the owner or renter of the home along with everyone related to them - whether through birth, marriage, or adoption. This includes relatives like spouses, children, parents, siblings, grandparents, and any other family members.
Households: A household includes all the people who occupy a housing unit (such as a house or apartment) as their usual place of residence.
Non Families: A nonfamily household is either someone living alone or when the owner/renter lives with people they aren't related to, like roommates.
Name
Median ↓
Mean
Married Families$141,390-
Families$127,734$141,731
Households$98,711$116,241
Non Families$48,505$57,900

$60,876

Average Income

$98,711

Median Household Income

5.89%

Poverty Rate

Nearby Cities

Sources

  1. US Census State Population Estimates - Most recent state estimates from the Census Bureau's Population Estimates Program
  2. US Census County Population Estimates - Most recent county estimates from the Census Bureau's Population Estimates Program
  3. American Community Survey (2009 - 2013)
  4. Census QuickFacts
  5. Historical Populations of States and Counties (1790 - 1990)