Black Hawk County is located in the northeastern part of Iowa. 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. The county encompasses approximately 576 square miles.
In 1995, Black Hawk County's population was 123,300 making it the fourth largest county in population in the state of Iowa. The majority of the county's population resides in the Waterloo-Cedar Falls metro area. Waterloo, the county seat, is located approximately 65 miles east of I-35 at the intersection of U.S. Highways 20, 63 and 218. The city of Cedar Falls is located approximately eight miles west of Waterloo.
Smaller cities and towns include Dunkerton, Elk Run Heights, Evansdale, Gilbertville, Hudson, LaPorte City and Raymond and portions of Jesup and Janesville. Unincorporated towns are Dewar, Eagle Center, Finchford, Glasgow, Washburn and Voorhies. There are 17 townships in the county; Barclay, Bennington, Big Creek, Black Hawk, Cedar, Cedar Falls, Eagle, East Waterloo, Fox, Lester, Lincloln, Mt Vernon, Orange, Poyner, Spring Creek, Union, Washington.