Biohazard Cleanup Near West Waterloo Waterloo, IL

Waterloo is a city in the St. Louis metropolitan area and is both the county seat and the largest city of Monroe County, Illinois.

Waterloo traces its roots to Bellefontaine, settled in the 1780s, which the city describes as the first permanent American settlement in the entire Northwest Territory.

Local legend says the name Waterloo was born in 1818 when Irishman Charles Carroll built his house on one side of the creek and his barn on the other and declared, "It won't be Bellefontaine, and it won't be Peterstown, but begorra, I'll give ye's both your Waterloo."

Waterloo became the Monroe County seat in 1825, when David H. Ditch's log home-turned-hotel was converted into the county courthouse.

In 1820 Emery Peters Rogers opened the area's first permanent store, mill, and quarry, anchoring the young settlement's economy.

A wave of German immigration in the 1840s gave Waterloo much of the German character it still keeps today.

Waterloo received its town charter on February 12, 1849, and was chartered as a city on August 29, 1888.

The Waterloo Historic District was placed on the National Register of Historic Places on December 1, 1978.

Waterloo had 11,013 residents at the 2020 census, up from 9,811 in 2010, bucking the population decline seen in much of downstate Illinois.

Census Bureau QuickFacts counts about 4,491 households in Waterloo (2020-2024), at about 2.43 people per household.