Buchanan County is a county located in the U.S. state of Iowa. As of the 2020 census, the population was 20,565. Its county seat is Independence. The county was created in 1837 and was named in honor of Senator James Buchanan, the 15th President of the United States.

Interstate 380 (I-380) is a 73-mile (117 km) auxiliary Interstate Highway in eastern Iowa. The route extends from I-80 near Coralville to Waterloo. I-380 connects the cities of Cedar Rapids and Waterloo, the state's second- and sixth-largest cities, respectively, to the Interstate Highway System. Except for its last 1.5 miles (2.4 km) north of U.S. Highway 20 (US 20), I-380 runs concurrently with Iowa Highway 27 (Iowa 27), which represents Iowa's portion of the 560-mile (900 km) Avenue of the Saints highway connecting Saint Louis, Missouri, with Saint Paul, Minnesota.