Fort Pierce South, FL has a population of 3,992 and is the 7,461st largest city in the United States. The population density is 1,444 per sq mi which is 392% higher than the Florida average and 1494% higher than the national average. The median age in Fort Pierce South is 47 which is approximately 13% higher than the Florida average of 42. In Fort Pierce South, 54% of the population over 15 years of age are married, 68% speak English and 28% speak Spanish. 41% of Fort Pierce South residents were born in Florida, 37% were born out of state, 4% were born outside of the United States and 18% were foreign born.