The term 'Great Lakes City' can refer to two cities in the United States: Erie, Pennsylvania and Gary, Indiana. Erie is a city located on the south shore of Lake Erie in northwestern Pennsylvania. It is the fourth-largest city in the state and the largest city in Northwestern Pennsylvania. Gary, Indiana is a city located on the southern shore of Lake Michigan in northwestern Indiana. It is the fifth-largest city in the state and the largest city in the Calumet Region.