Waterloo, Illinois

Waterloo population, 2020 to 2024

Waterloo added 161 residents from July 2020 to July 2024, a change of +1.5%. In the latest year it moved by -37. Among 330 Illinois places of 5,000 or more, that growth ranks 52nd; the median place changed by -0.9%. The median place of 5,000+ in Illinois has 14,760 people, so Waterloo is 76% of it.

Waterloo covers 8.29 square miles of land and 0.13 of water, for 1,347 people per square mile of land. The median Illinois place of 5,000+ has 2,177, so Waterloo is less dense than the typical town.

What county Waterloo is in

All of Waterloo's residents live in Monroe County, which had 34,969 residents in 2024. Waterloo holds 31.9% of the county's population. The shaded shape is on the map above; dots mark the eight nearest places.

ZIP codes in Waterloo

1 ZIP Code Tabulation Area (ZCTA) overlaps Waterloo by at least 10% of the ZCTA's or the city's land: 62298. ZCTAs are Census approximations of USPS ZIP code delivery areas. The list comes from the 2020 ZCTA to place relationship file, so a city that annexed land after 2020 may reach into ZIP codes not listed here.

Where Waterloo is

The Census internal point of Waterloo is at 38.341200, -90.152700. Springfield, the capital, is 103.1 miles NNE in a straight line. The nearest larger place is Arnold, MO (21,036 people), 13.1 miles away. The nearest city of 100,000 or more is St. Louis, MO, 20.9 miles away.

Daylight in Waterloo

At 38.34° N, Waterloo gets about 14 h 50 min of daylight around the June solstice and 9 h 30 min around the December solstice, a swing of 5 h 21 min. Figures are sunrise to sunset from the SunCalc model for June 21 and December 21, 2026.

Places near Waterloo

The eight nearest incorporated places of 1,000+ in Illinois, measured between internal points. The closest is Valmeyer, 8.3 miles away, with 1,214 people.