In April 1952 Congress ordered the Library of Congress to transfer the Declaration of Independence and Constitution to the National Archives.
The two documents were to go on public display in the National Archives Building along with the Bill of Rights, which was already at the Archives.
While the Archives exhibition hall had been specifically designed to display the two documents, it did not have a safe place to store the documents when they weren’t on exhibit.
The National Archives contracted with the Mosler Safe Company to construct a vault beneath the exhibition hall’s floor. At that time, an estimated 70 percent of all banks in the United States used Mosler safes and vaults.
Archives officials announced they would unveil the documents on Bill of Rights day that year.
This did not give the company much time.
Working under the looming deadline, Mosler engineers, technicians, and machinists worked around the clock to design and build a vault worthy of protecting the nation’s most valuable documents.
The company constructed the vault in Hamilton, Ohio, then brought it to Washington, DC, for installation.
The vault was made of steel and reinforced concrete. It was located about 20 feet beneath the floor of the exhibition hall. Built during the Cold War era, the vault was designed to be fireproof, shockproof, and bombproof.
During visiting hours, the three documents were displayed in then state-of-the art cases.
Every night, at the press of a button, the elevator gently lowered the documents in their cases through the floor into a 50-ton safe where they sat overnight.
The next morning, the elevator would again raise the documents for public viewing.
The two center pages of the Constitution, which were not exhibited, were also stored in the vault.
During the dedication ceremony on December 15, 1952, President Harry Truman said America’s treasured documents are “as safe from destruction as anything that the wit of modern man could devise.”
The Mosler Company also gave the National Archives a scale model of the vault, which was on display in the National Archives for many years.
The National Archives no longer uses the Mosler vault to protect the Charters of Freedom. The major renovation of the National Archives Building in the early 2000s included a complete overhaul of the security system safeguarding the Charters.
Read more about the transfer of the documents in the blog post “Carting the Charters.”