Prior to European exploration and settlement the Pinellas peninsula, like all of Tampa Bay, was inhabited by the Tocobaga Indians, who built a town and large temple mound overlooking the bay in what is now Safety Harbor. The modern site is protected and can be visited as part of the County's Philippe Park.
Spanish and British Florida
During the early 16th century Spanish explorers discovered and slowly began exploring Florida, including Tampa Bay. In 1528 Panfilo de Narvaez landed in Pinellas, and 10 years later Hernando de Soto is thought to have explored the Tampa Bay Area. By the early 18th century the Tocobaga had been virtually annihilated, having fallen victim to European diseases from which they had no immunity, as well as European conflicts. Later Spanish explorers named the area Punta Piñal (Spanish for "Point of Pines" or "Piney Point"). After trading hands between the British and the Spanish, Spain finally ceded Florida to the United States in 1821, and in 1823 the U.S. Army established Fort Brooke (later Tampa).
Settlement of West Hillsborough
In 1834 much of west central Florida, including the Pinellas peninsula (then known simply as West Hillsborough), was organized as Hillsborough County. The very next year Odet Philippe became the first permanent, non-native resident of the peninsula when he established a homestead near the site of the Tocobaga village in Safety Harbor. It was Philippe who first introduced both citrus culture and cigar-making to Florida.
Around the same time, the United States Army began construction of Fort Harrison, named after William Henry Harrison, as a rest post for soldiers from nearby Fort Brooke during the Second Seminole War. The new fort was located on a bluff overlooking Clear Water Harbor, which later became part of an early 20th-century residential development (now historic district) called Harbor Oaks. University of South Florida archaeologists excavated the site in 1977 after Alfred C. Wyllie discovered an underground ammunition bunker while digging a swimming pool on his estate. Clearwater would later become the first organized community on the peninsula as well as the site of its first post office.
The Armed Occupation Act, passed in 1842, encouraged further settlement of Pinellas, like all of Florida, by offering 160 acres (0.65 km2) to anyone who would bear arms and cultivate the land.. Pioneer families like the Booths, the Coachmans, the Marstons, and the McMullens established homesteads in the area in the years following, planting more citrus groves and raising cattle. During the American Civil War, many residents fought for the Confederate States of America. Brothers James and Daniel McMullen were members of the Confederate Cow Cavalry, driving Florida cattle to Georgia and the Carolinas to help sustain the war effort. John W. Marston served in the 9th Florida Regiment as apart of the Appomattox Campaign. Many other residents served in other capacities. Otherwise the peninsula had virtually no significance during the war, and the war largely passed the area by.
Tarpon Springs became West Hillsborough's first incorporated city in 1887, and in 1888 the Orange Belt Railway was extended into the southern portion of the peninsula. Railroad owner Peter Demens named the town that grew near the railroad's terminus St. Petersburg in honor of his hometown. The town would incorporate in 1892. Other major towns in the county incorporated during this time were Clearwater (1891), Dunedin (1899), and Largo (1905).
Construction of Fort De Soto, on Mullet Key facing the mouth of Tampa Bay, was begun in 1898 during the Spanish-American War to protect Tampa Bay from potential invading forces. The fort, a subpost of Fort Dade on adjacent Egmont Key (which lies in the mouth of Tampa Bay) was equipped with artillery and mortar batteries.
Birth of Pinellas County
Even into the early years of the 20th century, West Hillsborough had no paved roads, and transportation posed a major challenge. A trip to the county seat, across the bay in Tampa, was generally an overnight affair and the automobiles that existed on the peninsula at that time would frequently become bogged down in the muck after rainstorms. Angry at what was perceived as neglect by the county government, residents of Pinellas began a push to secede from Hillsborough. They succeeded, and on January 1, 1912 Pinellas County came into being. The peninsula, along with a small part of the mainland were incorporated into the new county.
Land boom and prohibition
Aviation history was made in St. Petersburg on January 1, 1914 when Tony Jannus made the world's first scheduled commercial airline flight with the St. Petersburg-Tampa Airboat Line from St. Petersburg to Tampa. The popular open-air St. Petersburg concert venue Jannus Landing memorializes the flight.
The early 1920s saw the beginning of a land boom in much of Florida, including Pinellas. During this period municipalities issued a large number of bonds to keep pace with the needed infrastructure, such as roads and bridges. The travel time to Tampa was cut in half—from —by the opening of the Gandy Bridge in 1924, along the same route Jannus' airline used. It was the longest automobile toll bridge in the world at the time.
Prohibition was unpopular in the area and the peninsula's countless inlets and islands became havens for rumrunners bringing in liquor from Cuba. Others distilled moonshine in the County's still plentiful woods.
Great Depression and World War II
Like much of Florida, the Great Depression came early to Pinellas with the collapse of the real estate boom in 1926. Local economies became severely stressed, and by 1930, St. Petersburg defaulted on its bonds. Only after World War II would significant growth return to the area. During the war, the area's tourist industry collapsed, but thousands of recruits came to the area when the U.S. military decided to use the area for training. Area hotels became barracks. The Renaissance Vinoy Hotel was used as an Army training school. The area's women and girls participated in the war effort as well. Hundreds of girls from the area's most prominent families formed a group called the Bomb-a-Dears, holding dances, socializing with recruits, and selling war bonds. After the war many of these same soldiers remembered their war time experience in Pinellas well, and returned as tourist or residents.
With the end of the Second World War, Pinellas would enter another period of rapid growth and development. In 1954 the original span of the Sunshine Skyway Bridge was opened, replacing earlier ferry service. By 1957 Clearwater was America's fastest growing city.
The Tampa Bay Regional Planning Council was founded by the late mayor of St. Petersburg, Herman Goldner, who sought without success during the 1960s to consolidate various municipalities and unincorporated areas in south Pinellas County. Each year the council presents its Herman Goldner Award for Regional Leadership.
Tragedy struck on May 9, 1980, when the southbound span of the original Sunshine Skyway Bridge was struck by the freighter MV Summit Venture during a storm, sending over of the bridge plummeting into Tampa Bay. The collision caused ten cars and a Greyhound bus to fall into the water, killing 35 people. The new bridge opened in 1987 and has since been listed as #3 of the "Top 10 Bridges" in the World by the Travel Channel.
The county operates a living history museum called Heritage Village containing more than 28 historic structures, some dating back to the 19th century, where visitors can experience what life was once like in Pinellas.
Pinellas County celebrated 100 years of existence on January 1, 2012.