Omer is a city in Arenac County in the U.S. state of Michigan. As of the 2010 census, the city population was 313. Though self-proclaimed through signage on US-23 as "Michigan's Smallest City," it is actually the second-smallest city in the state as of the 2010 census. The smallest city distinction as of 2010 belongs to Lake Angelus in northern Oakland County, with a population of 290.
According to the United States Census Bureau, the city has a total area of 1.2 square miles (3.2 km²), all land.
As of the census of 2000, there were 337 people, 143 households, and 98 families residing in the city. The population density was 272.2 per square mile (104.9/km²). There were 163 housing units at an average density of 131.7 per square mile (50.8/km²). The racial makeup of the city was 95.85% White, 1.19% Native American, 0.59% from other races, and 2.37% from two or more races. Hispanic or Latino of any race were 1.78% of the population.