Janesville is a city in Black Hawk and Bremer counties in the U.S. state of Iowa. It is part of the Waterloo–Cedar Falls Metropolitan Statistical Area.
Janesville is located on the county line between Bremer and Black Hawk counties, and is bisected by the Cedar River. The city has a total area of 1.49 square miles (3.86 km2), of which 1.44 square miles (3.73 km2) is land and 0.05 square miles (0.13 km2) is water.
A set of Kodachrome slides was found by Steven Martin that shows the girl’s basketball team of a high school in Janesville in the 1950s.