Dennison, OH has a population of 2,687 and is the 9,390th largest city in the United States. The population density is 1,992 per sq mi which is 673% higher than the Ohio average and 2099% higher than the national average. The median age in Dennison is 33 which is approximately 16% lower than the Ohio average of 39. In Dennison, 58% of the population over 15 years of age are married, 98% speak English and 1% speak Spanish. 83% of Dennison residents were born in Ohio, 16% were born out of state, 0% were born outside of the United States and 1% were foreign born.