Marissa, IL has a population of 1,666 and is the 12,094th largest city in the United States. The population density is 231 per sq mi which is 4% higher than the Illinois average and 155% higher than the national average. The median age in Marissa is 50 which is approximately 34% higher than the Illinois average of 37. In Marissa, 60% of the population over 15 years of age are married, 100% speak English and 0% speak Spanish. 79% of Marissa residents were born in Illinois, 21% were born out of state, 1% were born outside of the United States and 0% were foreign born.