Millersburg, IA has a population of 154 and is the 25,550th largest city in the United States. The population density is 1,140 per sq mi which is 1986% higher than the Iowa average and 1158% higher than the national average. The median age in Millersburg is 50 which is approximately 32% higher than the Iowa average of 38. In Millersburg, 56% of the population over 15 years of age are married, 95% speak English and 5% speak Spanish. 75% of Millersburg residents were born in Iowa, 23% were born out of state, 0% were born outside of the United States and 2% were foreign born.