city, seat (1905) of St. Lucie county, east-central Florida, U.S. It is situated on the Indian River (a lagoon connected to the Atlantic Ocean by inlets), about 55 miles (90 km) north of West Palm Beach. The fort (1838–42), built during the Seminole Wars, was named for Lieutenant Colonel Benjamin K. Pierce (brother of President Franklin Pierce (Pierce, Franklin)), who commanded a detachment. Permanent settlement began around the fort site in the 1860s, and the small fishing village of Edgartown and an oyster cannery were also established. In 1901 these entities were incorporated as the City of Fort Pierce. Pineapple growing was an early factor in the city's economic growth that was later replaced by citrus farming.

The city of Port St. Lucie, about 15 miles (25 km) south of Fort Pierce, was created and incorporated in 1961. A fast-growing residential city, it reached a population of more than 80,000 by the end of the 1990s. It was originally planned as a retirement community but now includes people of all ages.

Agriculture (citrus and cattle), fishing, light industry (including small engines), and food processing are the basis of the area's economy. Services (notably tourism and electronic retailing) are also important. The Port of Fort Pierce is on the Intracoastal Waterway and is a major shipping centre for citrus products. The city is the site of Indian River Community College (founded 1960). Artifacts and relics have been recovered from a sunken Spanish treasure fleet, lost in 1715 during a hurricane; some of these are on display at the St. Lucie County Historical Museum, and there is an underwater archaeological park in the area. Other attractions include Heathcote Botanical Gardens, the UDT-SEAL Museum (featuring weaponry and gear used by U.S. Navy divers), and the Harbor Branch Oceanographic Institution. Fort Pierce Inlet State Recreation Area is on a barrier island across the Indian River from the city. Sea turtles nest on area beaches in the summer, and manatees can be observed in the river from November to April. Pop. (1990) city, 36,830; Fort Pierce–Port St. Lucie MSA, 251,071; (2000) city, 37,516; Fort Pierce–Port St. Lucie MSA, 319,426.