Waterloo is a city located in Black Hawk County Iowa. It is also the county seat of Black Hawk County. With a 2020 population of 66,540, it is the 9th largest city in Iowa and the 574th largest city in the United States . Waterloo is currently declining at a rate of -0.59% annually and its population has decreased by -2.73% since the most recent census, which recorded a population of 68,406 in 2010. Waterloo reached it's highest population of in . Spanning over 63 miles, Waterloo has a population density of 1,084 people per square mile.
The average household income in Waterloo is $64,514 with a poverty rate of 17.42%. The median rental costs in recent years comes to $765 per month, and the median house value is $117,400. The median age in Waterloo is 36.8 years, 34.9 years for males, and 38.4 years for females.