Phosphate and the Port of Tampa

Phosphate gave Tampa a bulk export to ship beside its cigars and set off a boom that the City of Tampa says lasted through the 1890s.

The city's history page says that when phosphates were discovered nearby in the late 1880s, the resulting mining and shipping industries prompted a boom of growth and wealth that lasted through the 1890s. The University of Florida Libraries' Ingraham Expedition notes add that in the late 1880s Tampa became a major commercial city, exporting cigars and phosphate amongst other goods. That trade ran through two waterfronts that no longer handle it: Port Tampa, the rail and steamship terminal Henry Plant built south of the city, and Seddon Island, a dredged island at the foot of downtown where the Seaboard Air Line Railway put up a phosphate elevator. Seddon Island is now Harbour Island, and the City of Tampa annexed Port Tampa City on May 11, 1961.

The rock came from the Peace River valley in central Florida, where the Southwest Florida Water Management District dates the first find to 1881.

The district's history says Captain J. Francis LeBaron of the U.S. Army Corps of Engineers discovered phosphate in 1881 while surveying the Peace River south of Fort Meade. Additional deposits were discovered in 1886 by John C. Jones and Captain W.R. McKee, who quickly formed a company and commenced mining operations. The district calls the result the Florida phosphate boom of the late nineteenth century, sparked through a series of discoveries by amateur geologists and mining engineers.

The boom moved fast. Within a decade, more than 200 companies were mining phosphate in central Florida, and the price of an acre of Peace River land had soared from $1.25 to $300, according to the water management district. Phosphate was first mined with picks and shovels; as deeper reserves were identified, the companies began strip mining huge tracts with steam shovels, and by then the region was nicknamed Bone Valley because of the numerous fossils discovered in the deposits. The district explains that the phosphate formed millions of years ago, when Florida was underwater, and that phosphorus is a nonrenewable resource.

Port Tampa was a deepwater rail and steamship terminal about nine miles south of the city of Tampa, according to the UF Libraries Ingraham Expedition page.

The same page says the port was developed in large part by Henry Plant as a transportation hub for the Plant System's railway and steamboat lines, and that Plant had the channel deepened, extended the docks and built up the port's infrastructure. In the early 1890s Plant's South Florida Railroad had twice daily train service that connected Port Tampa with all points in the country by way of Sanford and Jacksonville, and steamships traveled weekly to Key West, Havana, Mobile and New Orleans. The City of Tampa credits Henry B. Plant's 1884 railroad extension to the Hillsborough River with opening new areas to development.

Plant paired the docks with hotels. The Ingraham notes list the Tampa Bay Hotel, opened in 1891, and the Port Tampa Inn on the pier to serve rail and steamer travelers. The City of Tampa's Port Tampa City page dates the town to 1887, when it was established as the end of the Henry Plant Railroad line, and names two Plant hotels beside the dock where trains stopped, the St. Elmo and the Port Tampa Inn; neither survives. The UF page gives the population of the Tampa metropolitan area as 5,532 in the 1890 Census and says it tripled by 1900, aided by Tampa's role in the Spanish American War. Members of the 1892 Everglades exploring party it documents rode the train from the Sanford region to Port Tampa and went on to Fort Myers aboard the Plant System steamship Tarpon.

Seddon Island was built for the port by dredging, and a 1981 note filed with a State Archives of Florida photograph says the Seaboard Air Line Railway's original contract there included a phosphate elevator.

The archival note says that dredging operations to improve Tampa's business as a port developed Seddon Island out of a natural sand flat, and that W.L. Seddon supervised the construction on the island for the Seaboard Air Line Railway, which gave the island its name. The original contract included a steel lift bridge, wharves, warehouses, railroad spurs and a phosphate elevator. The bridge was a 187 foot span designed by the Scherzer Rolling Lift Bridge Company of Chicago; it was installed in 1908 and provided railroad and vehicular access to the island.

The note also records that the phosphate elevator was modernized in 1947 and calls it a visual reminder of the importance of phosphate to the history of Tampa. Writing in Tampa Magazine in May 2020, historian Rodney Kite-Powell gives the same account of the Seaboard engineer and the Scherzer bridge put in place in 1908, and describes the island as an industrial site that was home to lumber yards and phosphate elevators. His dates for the island's creation and for the last phosphate shipments are not repeated in the state record checked for this page.

Both early terminals have left the phosphate trade, with Port Tampa absorbed into the city in 1961 and Seddon Island redeveloped as Harbour Island.

The City of Tampa says that on May 11, 1961, the City of Tampa annexed the area and Port Tampa City ceased to exist as a town. The city's page places the neighborhood directly north of MacDill Air Force Base, with its western border on Tampa Bay, and notes that the location was made famous as the debarkation point for the Spanish American War invasion of Cuba. Picnic Island Beach, in Port Tampa, is now a recreation area for canoeing and picnicking.

On Seddon Island, the State Archives record describes the condition of the port buildings in July 1981: the bridge was in good condition, the warehouses were deteriorated, and the warehouses and bridge were the oldest known structures of their type in the area. The archive's photograph, taken on May 1, 1984, looks southwest from the new bridge at the remains of the old railroad bridge as crews prepared to remove a structural truss element, and the State Archives files the scene under Harbour Island.

Fertilizer still moves through Port Tampa Bay, but the port's about page says energy has taken the baton from phosphate as Tampa Bay's top cargo.

Port Tampa Bay says mountains of fertilizer have moved out through the port ever since phosphate, the essential fertilizer component, was first discovered in Central Florida back in the late 1800s, and that some 150 years later it remains a cornerstone of port export activity. The port describes itself as a major fertilizer export port handling 33 million tons of cargo per year on 5,000 acres. It delivers nearly 15 million tons of petroleum products each year, and more than 45% of Florida's petroleum flows through the port. Its available cargo sites are on the main peninsula at Hooker's Point and at East Port, Port Sutton, Pendola Point, Port Ybor and along the downtown waterfront at Channelside, with satellite land at Port Redwing in southern Hillsborough County.

The two official descriptions measure the port differently. Port Tampa Bay calls itself Florida's largest port by tonnage, while the undated City of Tampa history page says Tampa's port is now the seventh largest in the nation and that phosphate shipping is supplemented by trade in shrimp; the city's line does not give the year or the measure behind its ranking.

Last verified: October 18, 2026, against the water management district's phosphate history, the UF Libraries Port Tampa page, two City of Tampa pages, the State Archives of Florida Seddon Island record and Port Tampa Bay's about page.