Omer is a city in Arenac County in the U.S. state of Michigan. The population was 274 at the 2020 census, which ranks it as the least-p…Omer is a city in Arenac County in the U.S. state of Michigan. The population was 274 at the 2020 census, which ranks it as the least-populated city in the state. Omer is consistently ranked as "Michigan's Smallest City" in terms of population, although the city of Lake Angelus held this distinction when it recorded a lower population at the 2010 census. Lake Angelus recorded a higher population of 287 at the 2020 census, making Omer again the state's least-populated city.