Richmond is a city on the border between Macomb and St. Clair counties within Metro Detroit and the U.S. state of Michigan. The population was 5,735 at the 2010 census. Most of the city is located in Macomb County, though there is a small portion in St. Clair County. The city is adjacent to Richmond Township and Lenox Township in Macomb County, although it is administratively autonomous. It is also adjacent to St.