Martensdale, IA has a population of 452 and is the 20,177th largest city in the United States. The population density is 1,187 per sq mi which is 2074% higher than the Iowa average and 1211% higher than the national average. The median age in Martensdale is 33 which is approximately 13% lower than the Iowa average of 38. In Martensdale, 49% of the population over 15 years of age are married, 99% speak English and 1% speak Spanish. 85% of Martensdale residents were born in Iowa, 15% were born out of state, 0% were born outside of the United States and 0% were foreign born.