Alpena is the only city in and the county seat of Alpena County, Michigan, United States. The population was 10,197 at the 2020 census, making it the third most populated city in the Northern Michigan region, after Traverse City and Cadillac. The city is surrounded by Alpena Township, but the two are administered autonomously. It is the core city of the Alpena micropolitan statistical area, which encompasses all of Alpena County and had a total population of 28,907 at the 2020 census.