Dubuque is a city in Dubuque County, Iowa, United States. As of the 2000 census, the city had a population of 57,686. It is the county seat of Dubuque County^GR6. Dubuque is located on the Mississippi River. The city is the center of a small metro area known locally as "The Tri-State Area." It is located at the point where Iowa, Wisconsin and Illinois meet. Adjacent towns include Asbury, Sageville, Key West and Peosta, Iowa, and East Dubuque, Illinois.

The city is located at the junction of U.S. Highways 20, 61, 52 and 151, and Iowa Highway 3. It is served by the Chicago Central & Pacific Railroad (a subsidiary of the Canadian National Railway), the BNSF Railway, and the Iowa, Chicago & Eastern Railroad. American Airlines provides service between Dubuque and O'Hare International Airport in Chicago from the Dubuque Regional Airport, located about seven miles south of Dubuque along U.S. Highway 61.

Dubuque is often called "The Key City." It is also known as the City of Five Flags for the five different flags — English, Spanish, Royal French, Republican French, and American — which since the 1600s have flown over the land on which Dubuque now sits.

Two ships of the US Navy have been named USS Dubuque after the city. The latter is still on active duty.