The seat and largest city is Dubuque. It borders Clayton, Jackson, Jones and Delaware Counties in Iowa, Grant County in Wisconsin and Jo Daviess County in Illinois.
Major highways include US-20, US-52, US-61, US-151, IA-3 and IA-32.
Cities
Balltown
Dubuque
Dyersville
Epworth
Farley
Graf
Massey
Peosta
Sageville
West Dubuque