Waterloo is a city in and the county seat of Black Hawk County, Iowa, United States. As of the 2020 United States Census the population was 67,314, making it the eighth-most populous city in the state.
Thomas Leonard Carroll was an American bank robber and Depression-era outlaw. A boxer-turned-criminal, he committed numerous robberies during the 1920s and 1930s as well as being a longtime member of the Dillinger gang.