Construction on the Pinellas Trail began in 1990 but the right of way that became the trail has a rich history in the development of Florida's West Coast and Pinellas County. Petrovitch A. Demenscheff, born 1850 in St. Petersburg, Russia, first cousin of Prince Petroff of Petrograd, immigrated to America in 1880. He changed his name to Peter Demens and became one of the biggest contractors in the state. Work with the Orange Belt Railway resulted in his ownership of the company when they couldn't pay for his work. 

The Orange Belt Railway line reached Tarpon Springs in January 13, 1888. By May 1st the tracks reached St. Petersburg, named by Demens after his birthplace. In 1893 the Orange Belt changed to the Sanford and St. Petersburg Railroad until 1895 when it was purchased by Henry Plant who incorporated it into the Plant System Railroad and upgraded the gauge from narrow to standard.

That original line from Tarpon Springs to Clearwater forms the right of way of the north section of the Pinellas Trail. From Clearwater the original rail line swings southeast through Central Largo to St. Petersburg and is still a functioning CSX rail line today. 

On January 15, 1897 Henry Plant opened the Belleview Biltmore Hotel and extended a spur from Clearwater south to the hotel for the private cars of his clients and railroad executives. That section of line is now the Pinellas Trail. Plant died in 1899 and the Atlantic Coast Line Railroad took over. ACL extended the line south from the Belleview Biltmore in 1915 through what is now Seminole. The line served the citrus growers of the area and provided rail service to the Bay Pines Veterans Hospital built in 1932. ACL operated regular passenger and freight service over this route until July 1, 1967 when they merged with Seaboard Air Line Railroad thus becoming the Seaboard Coast Line Railroad. 

SCL became a subsidiary of CSX in 1980. On May 2, 1980 a fisherman on the creosote-soaked Cross Bayou trestle at Bay Pines carelessly dropped a cigarette and started a fire. The blaze completely destroyed the bridge.

Unwilling to replace the trestle CSX ended service on that section of railroad between Clearwater and west St. Petersburg forever. They eventually gave the right of way to Pinellas County thus opening the opportunity for creation of a bicycle trail. The Pinellas Trail opened its first section from Seminole City Park to Taylor Park in Largo on Tuesday November 27, 1990.  

The trail looking south just north of Park Boulevard