<P> More than 95 percent of the land area lies in Monroe County, but a small portion extends northeast into Miami - Dade County, such as Totten Key . The total land area is 137.3 square miles (356 km). As of the 2010 census the population was 73,090 with an average density of 532.34 per square mile (205.54 / km), although much of the population is concentrated in a few areas of much higher density, such as the city of Key West, which has 32% of the entire population of the Keys . The US Census population estimate for 2014 is 77,136 . </P> <P> The city of Key West is the county seat of Monroe County . The county consists of a section on the mainland which is almost entirely in Everglades National Park, and the Keys islands from Key Largo to the Dry Tortugas . </P> <P> The Keys were originally inhabited by Calusa and Tequesta Native Americans, and were later charted by Juan Ponce de León in 1513 . De León named the islands Los Martires ("The Martyrs"), as they looked like suffering men from a distance . "Key" is derived from the Spanish word cayo, meaning small island . For many years, Key West was the largest town in Florida, and it grew prosperous on wrecking revenues . The isolated outpost was well located for trade with Cuba and the Bahamas, and was on the main trade route from New Orleans . Improved navigation led to fewer shipwrecks, and Key West went into a decline in the late nineteenth century . </P> <P> The Keys were long accessible only by water . This changed with the completion of Henry Flagler's Overseas Railway in the early 1910s . Flagler, a major developer of Florida's Atlantic coast, extended his Florida East Coast Railway down to Key West with an ambitious series of oversea railroad trestles . Three hurricanes disrupted the project in 1906, 1909, and 1910 . </P>

Why is the florida keys called the keys
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