Plain City, UT has a population of 6,183 and is the 5,644th largest city in the United States. The population density is 518 per sq mi which is 1440% higher than the Utah average and 472% higher than the national average. The median age in Plain City is 33 which is approximately 10% higher than the Utah average of 30. In Plain City, 75% of the population over 15 years of age are married, 98% speak English and 1% speak Spanish. 83% of Plain City residents were born in Utah, 17% were born out of state, 0% were born outside of the United States and 0% were foreign born.