Located 68 miles (109 km) west of Key West, in Gulf of Mexico
Nearly thirty years in the making (1846-1875), Fort Jefferson was never finished nor fully armed. It is the largest brick masonry structure in the Americas, and is composed of over 16 million bricks, the building covers 16 acres (6.5 ha).
Fort Jefferson was built to protect one of the most strategic deepwater anchorages in North America. By fortifying this spacious harbor, the United States maintained an important “advance post” for ships patrolling the Gulf of Mexico and the Straits of Florida. Nestled within the islands and shoals that make up the Dry Tortugas, the harbor offered ships the chance to resupply, refit, or seek refuge from storms.
The location of the Tortugas along one the world’s busiest shipping lanes was its greatest military asset. Though passing ships could easily avoid the largest of Fort Jefferson’s guns, they could not avoid the warships that used its harbor.
During the Civil War, Union warships used the harbor in their campaign to blockade Southern shipping. The fort was also used as a prison, mainly for Union deserters. Its most famous prisoner was Dr. Samuel Mudd, the physician who set the broken leg of John Wilkes Booth.
Fort Jefferson is no longer in use as a military facility and is currently part of the Dry Tortugas National Park. Fort Jefferson can be reached by a daily ferry from Key West, as well as by chartered seaplane and private yacht. As a national park, basic camping is allowed on the beach. Camping is very limited, so make your reservation now. Visitors by ferry typically spend 4 hours on the island, which is enough time for a guided tour of the fort, lunch on the boat and a swim (snorkel equipment provided) on the reef. Within the fort are a museum and bookstore.