Fort Jefferson, Garden Key, Key West, Monroe County, FL

Fort Jefferson was part of Fort Jefferson National Monument from 1935 to 1992. Since then it has been part of Dry Tortugas National Park. The address for the survey has been updated to reflect this change.
Significance: As initially designed by Chief Engineer of the U.S. Army General Joseph Totten, Fort Jefferson was to have independent free-standing powder magazines on the Parade Ground, with small, readily accessible magazines occupying two casemates of each long curtain wall and in each tower bastion. The bastions, located to each corner of the fort, project outward to allow defensive fire in many directions. The bastions also contain a granite spiral stairway providing access to all three tiers of the fort. Totten's plans for the fort were approved by the Secretary of War on November 16, 1846. However, the final plans for the Large and Small magazines that were to serve as the main and secondary powder storage facilities were not developed until 1861, and their construction not begun until 1865. In fact, when Superintending Engineer, Montgomery C. Meigs arrived in November 1860 he reported that not a single gun could be found. By January of the following year, however, the first guns had arrived. This occurred shortly after Florida announced its secession from the Union and only months before the outbreak of the Civil War. Thus, through out the Civil War, when Fort Jefferson served as a coastal blockade for Union naval forces and a military prison, the curtain and tower bastion magazines provided the only viable powder storage. Despite armament upgrades in 1872-73, advancements in weaponry made Fort Jefferson obsolete, and the military abandoned
it in 1876.
Survey number: HABS FL-44
Building/structure dates: 1861 Subsequent Work
Building/structure dates: 1865 Subsequent Work
Building/structure dates: 1872- 1873 Subsequent Work
Building/structure dates: 1846 Initial Construction
National Register of Historic Places NRIS Number: 70000069, 01000228