Near Key West in Monroe County, Florida — The American South (South Atlantic)

Keeping Powder Dry and Safe

Fort Jefferson

— Dry Tortugas National Park —

Keeping Powder Dry and Safe Marker image. Click for full size.

Photographed by Vince Jackson, March 4, 2022

1. Keeping Powder Dry and Safe Marker

Inscription. A fort's effectiveness in the 1800s depended in large part on its gunpowder supply. Keeping the powder dry and avoiding explosions were critical. This powder magazine's special features included wooden floors and walls to prevent sparks, and vents and raised flooring to enhance air circulation. The impressive arch above you was designed to support a thick roof of protective concrete.

If this and four other magazines planned for the parade ground had been completed, they would have supplied powder to warships using the anchorage. The 32 magazines built within the walls of the fort stored powder for the fort's guns. The detached magazines would have supplemented them if necessary.

Barrels of powder should not be rolled... they should be carried in hand-barrows, or slings made of rope or leather.
Artillerist's Manual, 1st Lt. John Gibbon, US Army, 1860

(captions)
The foundations visible around you would have supported the first floor of this magazine.
Raised wooden floor
Wood-covered walls
Vault
Concrete
Entrance barrier (or shot porch)

Erected by National Park Service, U.S. Department of the Interior.

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Topics. This historical marker is listed in these topic lists: Forts and Castles • Parks & Recreational Areas • War, US Civil.

Location. 24° 37.762′ N, 82° 52.36′ W. Marker is near Key West, Florida, in Monroe County. It can be reached from no nearby street. Touch for map. Marker is at or near this postal address: Fort Jefferson - Key West, Key West FL 33040, United States of America. Touch for directions.

Regionally, this marker is on the Florida Keys.

It is also in the American South

and on the Gulf Coast.

Globally, it is in the North Atlantic Region,

North America,

a Gulf of Mexico state,

the Western Hemisphere,

the Western World,

and the Anglosphere.

Historically, it finds itself in what was once New Spain,

the territory of the Mississippian Culture,

one of the Confederate States of America,

and the Antebellum South.

Other nearby markers. At least 8 other markers are within walking distance of this marker: The Hospital (a few steps from this marker); Defending US Commerce (within shouting distance of this marker); Catching Rain (within shouting distance

Photographed by Vince Jackson, March 4, 2022

2. Keeping Powder Dry and Safe Marker

Interior of the remote magazine.

of this marker); Parade Ground Panorama (within shouting distance of this marker); Red-Hot Cannonballs (within shouting distance of this marker); Traverse Magazine (within shouting distance of this marker); Soldiers' Barracks (about 300 feet away, measured in a direct line); The Moat (about 300 feet away). Touch for a list and map of all markers in Key West.

Also see . . . Dry Tortugas National Park. National Park Service (Submitted on March 14, 2022.)

Photographed by Vince Jackson, March 4, 2022

3. Keeping Powder Dry and Safe Marker

Exterior of the remote powder magazine.

Credits. This page was last revised on January 14, 2026. It was originally submitted on March 11, 2022, by Vince Jackson of Toano, Virginia. This page has been viewed 300 times since then and 20 times this year. Photos: 1, 2, 3. submitted on March 11, 2022, by Vince Jackson of Toano, Virginia. • Bernard Fisher was the editor who published this page.