Marco Island, FL has a population of 17,361 and is the 2,484th largest city in the United States. The population density is 1,428 per sq mi which is 386% higher than the Florida average and 1476% higher than the national average. The median age in Marco Island is 65 which is approximately 56% higher than the Florida average of 42. In Marco Island, 76% of the population over 15 years of age are married, 86% speak English and 7% speak Spanish. 8% of Marco Island residents were born in Florida, 77% were born out of state, 1% were born outside of the United States and 14% were foreign born.