High Quality Content by WIKIPEDIA articles! Bay City is a city in Bay County, Michigan, located near the base of the Saginaw Bay on Lake Huron. As of the 2010 census, the city`s population was 34,932, and is the principal city of the Bay City Metropolitan Statistical Area, which is included in the Saginaw-Bay City-Saginaw Township North Combined Statistical Area. The city, along with nearby Midland and Saginaw, form the "Tri-Cities" region, which has more recently been called the "Great Lakes Bay" region.