Treasure Island, FL has a population of 6,827 and is the 5,267th largest city in the United States. The population density is 4,416 per sq mi which is 1404% higher than the Florida average and 4775% higher than the national average. The median age in Treasure Island is 57 which is approximately 38% higher than the Florida average of 42. In Treasure Island, 67% of the population over 15 years of age are married, 86% speak English and 5% speak Spanish. 19% of Treasure Island residents were born in Florida, 70% were born out of state, 1% were born outside of the United States and 9% were foreign born.