Key Largo is an island in the upper Florida Keys archipelago and is the largest section of the Keys, at 33 miles (53 km) long. It is one of the northernmost of the Florida Keys in Monroe County, and the northernmost of the Keys connected by U.S. Highway 1 (the Overseas Highway). Its earlier Spanish name was Cayo Largo, meaning long islet.
Key Largo is connected to the mainland in Miami-Dade County by two routes. The first route is The Overseas Highway, which is U.S. Highway 1 that enters Key Largo at Jewfish Creek near the middle of the island and turns southwest. The second route is Card Sound Road, which connects to the northern part of Key Largo at Card Sound Bridge and runs southeastward to connect with County Road 905, which runs southwest and joins U.S. 1 at about mile marker 106. These routes originate at Florida City on the mainland.
Key Largo is a popular tourist destination and calls itself the "Diving Capital of the World" because the living coral reef a few miles offshore attracts thousands of scuba divers and sport-fishing enthusiasts.
In 1896, a post office opened on Key Largo called Aiken, located near Sound Point.
Key Largo's proximity to the Everglades also makes it a premier destination for kayakers and ecotourists. Automotive and highway pioneer and Miami Beach developer Carl G. Fisher built the Caribbean Club in 1938 as his last project.
The island gained fame as the setting for the 1948 film Key Largo, but apart from background filming used for establishing shots, the film was shot on a Warner Brothers sound stage in Hollywood. After the film's success, pressure from local businesses resulted in a change in the name of the post office serving the northern part of the island, from "Rock Harbor" to "Key Largo", on June 1, 1952. After that, every resident north of Tavernier had a Key Largo address and the cancellation read "Key Largo".