Mansfield, IL has a population of 848 and is the 16,201st largest city in the United States. The population density is 1,607 per sq mi which is 623% higher than the Illinois average and 1674% higher than the national average. The median age in Mansfield is 48 which is approximately 29% higher than the Illinois average of 37. In Mansfield, 69% of the population over 15 years of age are married, 95% speak English and 3% speak Spanish. 82% of Mansfield residents were born in Illinois, 17% were born out of state, 0% were born outside of the United States and 2% were foreign born.