Clarktown, OH has a population of 656 and is the 17,867th largest city in the United States. The population density is 321 per sq mi which is 25% higher than the Ohio average and 254% higher than the national average. The median age in Clarktown is 57 which is approximately 46% higher than the Ohio average of 39. In Clarktown, 71% of the population over 15 years of age are married, 100% speak English and 0% speak Spanish. 90% of Clarktown residents were born in Ohio, 10% were born out of state, 0% were born outside of the United States and 0% were foreign born.