The Plains, OH has a population of 2,918 and is the 8,945th largest city in the United States. The population density is 1,280 per sq mi which is 397% higher than the Ohio average and 1313% higher than the national average. The median age in The Plains is 38 which is approximately 4% lower than the Ohio average of 39. In The Plains, 49% of the population over 15 years of age are married, 95% speak English and 1% speak Spanish. 78% of The Plains residents were born in Ohio, 20% were born out of state, 0% were born outside of the United States and 2% were foreign born.