Mattoon, IL has a population of 17,399 and is the 2,483rd largest city in the United States. The population density is 1,688 per sq mi which is 659% higher than the Illinois average and 1763% higher than the national average. The median age in Mattoon is 40 which is approximately 6% higher than the Illinois average of 37. In Mattoon, 49% of the population over 15 years of age are married, 98% speak English and 1% speak Spanish. 82% of Mattoon residents were born in Illinois, 16% were born out of state, 1% were born outside of the United States and 1% were foreign born.