Black Hawk County is a county in the northeastern part of U.S. state of Iowa. As of the 2020 census, the population was 131,144, making it Iowa's fifth-most populous county. The county seat is Waterloo. Black Hawk County is part of the Waterloo-Cedar Falls, IA Metropolitan Statistical Area. History Black Hawk County was formed on February 17, 1853, from sections of Buchanan County. It was named after Black Hawk, a Sauk leader during the 1832 Black Hawk War. Geography According to the U.S. Census Bureau, the county has an area of , of which is land and (1.2%) is water. The Cedar River roughly divides the county in half from the northwest to the southeast corner. The land is mostly level since much of it is on the river's flood plain. Major highways Interstate 380 U.S. Highway 20 U.S. Highway 63 U.S. Highway 218 Iowa Highway 21 Iowa Highway 27 Iowa Highway 57 Iowa Highway 58 Iowa Highway 175 Iowa Highway 281 Transit Metropolitan Transit Authority of Black Hawk County List of intercity bus stops in Iowa Adjacent counties Bremer County (north) Buchanan County (east) Benton County (southeast) Tama County (southwest) Grundy County (west) Butler County (northwest) Fayette County (northeast) Demographics 2020 census The 2020 census recorded a population of 131,144 in the county, with a population density of . 94.55% of the population reported being of one race. 73.49% were non-Hispanic White, 10.43% were Black, 4.92% were Hispanic, 0.32% were Native American, 2.61% were Asian, 0.65% were Native Hawaiian or Pacific Islander and 7.57% were some other race or more than one race. There were 58,559 housing units of which 54,223 were occupied. 2010 census The 2010 census recorded a population of 131,090 in the county, with a population density of . There were 55,887 housing units, of which 52,470 were occupied. 2000 census At the 2000 census there were 128,012 people, 49,683 households, and 31,946 families in the county. The population density was . There were 51,759 housing units at an average density of 91 per square mile (35/km2). The racial makeup of the county was 88.42% White, 7.95% Black or African American, 0.18% Native American, 0.98% Asian, 0.04% Pacific Islander, 0.93% from other races, and 1.49% from two or more races. 1.84%. were Hispanic or Latino of any race. Of the 49,683 households 29.50% had children under the age of 18 living with them, 50.20% were married