USBD meaning in Regional ?

The United States Bullion Depository, often known as Fort Knox, is a fortified vault building located next to the United States Army post of Fort Knox, Kentucky. It is operated by the United States Department of the Treasury. The vault is used to store a large portion of the United States' gold reserves as well as other precious items belonging to or in custody of the federal government. It currently holds roughly 147 million troy ounces (4,580 metric tons) of gold bullion, over half of the Treasury's stored gold. The United States Mint Police protects the depository.

The Treasury built the depository in 1936 on land transferred to it from the military. Its purpose was to house gold then stored in New York City and Philadelphia, in keeping with a strategy to move gold reserves away from coastal cities to areas less vulnerable to foreign military attack. The first set of gold shipments to the depository occurred during the first half of 1937. A second set was completed in 1941. These shipments, overseen by the United States Post Office Department, totaled roughly 417 million troy ounces (12,960 metric tons), almost two-thirds of the total gold reserves of the United States.

During World War II the signed original Constitution of the United States, Declaration of Independence, Articles of Confederation, Lincoln's Second Inaugural Address and drafts of Lincoln's Gettysburg Address were stored in its vault for protection, as was a Gutenberg Bible and an exemplified copy of Magna Carta. After the war, the depository held the Crown of St. Stephen as well as stockpiles of opium and morphine. Today it is known to hold ten 1933 Double Eagle gold coins, a 1974-D aluminum penny, and twelve gold (22-karat) Sacagawea dollar coins that flew on the Space Shuttle Columbia, specifically STS-93 in 1999.

The depository is a secure facility. Between its fenced perimeter and granite lined concrete structure lie rings of razor wire and minefields. The grounds are monitored by high-resolution night vision video cameras and microphones. The subterranean vault is made of steel plates, I-beams and cylinders encased in concrete. Its torch-and-drill resistant door is 21 inches (53 cm) thick and weighs 20 short tons (18 metric tons). The vault door is set on a 100-hour time lock, and can only be opened by members of the depository staff who must dial separate combinations. Visitors are not allowed inside. It is so secure that the term "as safe as Fort Knox" has become a metaphor for safety and security.