Richmond is a city within Metro Detroit in the U.S. state of Michigan. The population was 5,878 at the 2020 census. Most of the city is located i…Richmond is a city within Metro Detroit in the U.S. state of Michigan. The population was 5,878 at the 2020 census. Most of the city is located in Macomb County, though there is a small portion in neighboring St. Clair County.