Waterloo is a city in and the county seat of Black Hawk County, Iowa, United States. As of the 2010 United States Census the population decreased by 0.5% to 68,406; the 2019 Census estimates the population at 67,328, making it the eighth-largest city in the state. The city is part of the Waterloo – Cedar Falls Metropolitan Statistical Area, and is the more populous of the two cities.
Waterloo was originally known as Prairie Rapids Crossing. The town was established near two Meskwaki American tribal seasonal camps alongside the Cedar River. It was first settled in 1845 when George and Mary Melrose Hanna and their children arrived on the east bank of the Red Cedar River (now just called the Cedar River). They were followed by the Virden and Mullan families in 1846. Evidence of these earliest families can still be found in the street names Hanna Boulevard, Mullan Avenue and Virden Creek.
On December 8, 1845, the Iowa State Register and Waterloo Herald was the first newspaper published in Waterloo.
The name Waterloo supplanted the original name, Prairie Rapids Crossing, shortly after Charles Mullan petitioned for a post office in the town. Since the signed petition did not include the name of the proposed post office location, Mullan was charged with selecting the name when he submitted the petition.