Merrill, IA has a population of 829 and is the 16,348th largest city in the United States. The population density is 1,463 per sq mi which is 2578% higher than the Iowa average and 1515% higher than the national average. The median age in Merrill is 43 which is approximately 12% higher than the Iowa average of 38. In Merrill, 66% of the population over 15 years of age are married, 91% speak English and 7% speak Spanish. 78% of Merrill residents were born in Iowa, 15% were born out of state, 1% were born outside of the United States and 7% were foreign born.