Allegan, MI has a population of 5,051 and is the 6,429th largest city in the United States. The population density is 1,313 per sq mi which is 1202% higher than the Michigan average and 1349% higher than the national average. The median age in Allegan is 35 which is approximately 12% lower than the Michigan average of 40. In Allegan, 53% of the population over 15 years of age are married, 98% speak English and 1% speak Spanish. 84% of Allegan residents were born in Michigan, 15% were born out of state, 0% were born outside of the United States and 0% were foreign born.