- Dubuque (/dəˈbjuːk/, dəb-YOOK) is a city in and the county seat of Dubuque County, Iowa, United States, located along the Mississippi River. At the time of the 2020 census, the population of Dubuque was 59,667. The city lies at the junction of Iowa, Illinois, and Wisconsin, a region locally known as the Tri-State Area. It serves as the main commercial, industrial, educational, and cultural center for the area. Geographically, it is part of the Driftless Area, a portion of North America that escaped all three phases of the Wisconsin Glaciation.