Florida Keys

The Florida Keys are a coral cay archipelago located off the southern coast of Florida.

They form the southernmost part of the continental United States. The islands begin near the southeastern coast of the Florida peninsula, south of Miami. They extend in an arc toward the south-southwest and then westward. This chain leads to Key West, which is the westernmost inhabited island. The islands continue on to the uninhabited Dry Tortugas.

This chain of islands sits along the Florida Straits. It divides the Atlantic Ocean from the Gulf of Mexico. The islands also define one edge of Florida Bay.

The geology of the Keys is a result of ancient biological processes and changing sea levels.

The northern and central sections consist of Key Largo Limestone. This is the exposed part of an ancient coral reef. The northernmost island in this formation is Elliott Key. North of that, small transitional keys exist. These are made of sand built around exposed ancient reef. Further north, islands like Key Biscayne are barrier islands made of sand. The southwestern islands, from Big Pine Key to the Marquesas Keys, consist of Miami Limestone. This limestone formed from eroded reef material and skeletal remains of bryozoans. These materials settled in a shallow sea to form an oolitic deposit.

Sea level changes during recent glaciations shaped the current landscape.

About 130,000 years ago, the Sangamonian Stage raised sea levels. This covered southern Florida in a shallow sea. Parallel reef lines formed along the edge of the submerged Florida Platform. These reefs stretched from the Miami area to the Dry Tortugas. Minor fluctuations in sea level then exposed these reefs to erosion. Acidic water from decaying vegetation can dissolve the limestone. This process creates holes where soil accumulates and trees can take root. Some dissolved limestone redeposited as a dense layer called caprock. This caprock covers parts of the Key Largo and Miami limestones.

Human history in the Keys began with the Calusa and Tequesta people.

In 1513, Juan Ponce de León charted the islands. He named them "Los Martires," which means "The Martyrs" in Spanish. The name "Key" comes from the Spanish word "cayo," meaning small island. For a long time, Key West was a prosperous town. It grew wealthy through wrecking revenues from ships. The location was perfect for trade with the Bahamas and Cuba. It also sat on the main trade route from New Orleans. However, better navigation led to fewer shipwrecks. This caused the economy of Key West to decline in the late nineteenth century.

Transportation to the islands changed significantly in the early 1910s.

Henry Flagler built the Overseas Railway to connect the islands. He used an ambitious series of railroad trestles to reach Key West. This project faced many disruptions from hurricanes in 1906, 1909, and 1910. The most devastating event was the Labor Day hurricane of 1935. This was a Category 5 storm with winds reaching 165 mph. It produced a storm surge over 15 feet high. The storm killed over 400 people, though some estimates say more than 600. It also destroyed the Overseas Railway. The damaged tracks were never rebuilt. Instead, the Overseas Highway, or U.S. Highway 1, was created to replace the rail.

Modern infrastructure includes the famous Seven Mile Bridge.

This bridge connects Knight's Key to Little Duck Key. The concrete bridge is about 6.79 miles long. The current bridge bypasses Pigeon Key. Pigeon Key once housed workers for Flagler's railway in the 1900s. An old section of the bridge still provides access to the island. However, that section was closed to vehicles in 2008. The highway now allows travelers to see exotic plants and animals. It also provides access to the largest coral reef chain in the United States. The Florida Reef extends from Fowey Rocks to the south of the Marquesas Keys. It is the third-largest barrier reef system in the world.

The environment of the Keys is unique and tropical.

The climate is closer to the Caribbean than the rest of Florida. The islands feature upland forests, inland wetlands, and shoreline zones. You can find species here that exist nowhere else on the US mainland. One such animal is the Key Deer.

The population of the Keys has grown steadily over time. The 2010 census recorded 73,090 people. By 2020, the population estimate reached 82,874. Most people live in concentrated areas like the city of Key West. Key West is the county seat of Monroe County. The islands remain a place of great natural and historical interest.