Port St. Lucie, FL has a population of 175,652 and is the 139th largest city in the United States. The population density is 1,476 per sq mi which is 403% higher than the Florida average and 1530% higher than the national average. The median age in Port St. Lucie is 41 which is approximately 1% lower than the Florida average of 42. In Port St. Lucie, 57% of the population over 15 years of age are married, 76% speak English and 16% speak Spanish. 32% of Port St. Lucie residents were born in Florida, 47% were born out of state, 3% were born outside of the United States and 18% were foreign born.