Ontonagon, MI has a population of 1,504 and is the 12,667th largest city in the United States. The population density is 407 per sq mi which is 304% higher than the Michigan average and 350% higher than the national average. The median age in Ontonagon is 57 which is approximately 44% higher than the Michigan average of 40. In Ontonagon, 64% of the population over 15 years of age are married, 97% speak English and 1% speak Spanish. 70% of Ontonagon residents were born in Michigan, 24% were born out of state, 1% were born outside of the United States and 5% were foreign born.