Fort Madison, IA has a population of 10,769 and is the 3,732nd largest city in the United States. The population density is 1,135 per sq mi which is 1977% higher than the Iowa average and 1152% higher than the national average. The median age in Fort Madison is 43 which is approximately 12% higher than the Iowa average of 38. In Fort Madison, 54% of the population over 15 years of age are married, 98% speak English and 2% speak Spanish. 72% of Fort Madison residents were born in Iowa, 25% were born out of state, 1% were born outside of the United States and 1% were foreign born.