Merwin, MO has a population of 27 and is the 28,664th largest city in the United States. The population density is 184 per sq mi which is 113% higher than the Missouri average and 103% higher than the national average. The median age in Merwin is 45 which is approximately 17% higher than the Missouri average of 38. In Merwin, 56% of the population over 15 years of age are married, 100% speak English and 0% speak Spanish. 74% of Merwin residents were born in Missouri, 26% were born out of state, 0% were born outside of the United States and 0% were foreign born.