Marquette Heights, IL has a population of 2,891 and is the 8,993rd largest city in the United States. The population density is 2,927 per sq mi which is 1217% higher than the Illinois average and 3131% higher than the national average. The median age in Marquette Heights is 34 which is approximately 8% lower than the Illinois average of 37. In Marquette Heights, 64% of the population over 15 years of age are married, 99% speak English and 0% speak Spanish. 86% of Marquette Heights residents were born in Illinois, 14% were born out of state, 0% were born outside of the United States and 0% were foreign born.