Now, because Washington fears that China got its hands on U.S. nuclear secrets, these bleary-eyed declassifiers could face a daunting new task: Doing it again.
Legislation headed for approval in Congress would require all of the documents to be re-examined to make sure that sensitive details about the U.S. nuclear arsenal don't slip out of the government's attic.
"This is all part of the frenzy about Chinese espionage that is driving Washington crazy," said Steven Aftergood, who directs The Project on Government Secrecy at the Federation of American Scientists. "The idea that they're going to reread material that's already been declassified is preposterous. It will basically cripple the declassification program by driving it in circles."
Present efforts to lift the veil of government secrecy are driven by an executive order President Clinton signed in 1995. The order instructs federal agencies to open - by April 2000 - classified records that contain historical material and are more than 25 years old. Exceptions are narrowly defined.
In the past three years, more than 600 million pages have been declassified.
Subjects range from the Cold War to Vietnam, POWs to UFOs. Researchers are rewriting history with new information about the U.S.-Soviet arms race, the failed Bay of Pigs invasion of Cuba, a 1973 coup in Chile, covert action around the globe, and more.
The public already can access 400 million pages that have been unsealed. Another 200 million pages are declassified, but are not yet on public shelves. Nearly 1 billion more pages still must be reviewed.
Declassification was moving at a fast clip until last year when some lawmakers worried that nuclear secrets - still classified under the Atomic Energy Act - weren't being properly protected. Sens. Jon Kyl, R-Ariz.; Richard Shelby, R-Ala., and Bob Smith, I-N.H., wrote to National Security Adviser Samuel Berger saying that "in a frenzied attempt" to meet the April 2000 deadline, documents containing sensitive nuclear weapons information may have been released, or were in danger of being released.
Such concerns prompted Congress to pass a law last year requiring declassifiers to come up with a plan to scan documents, page-by-page, looking for nuclear material - unless the records were "highly unlikely" to contain such information.
This year, after a government scientist suspected of giving nuclear secrets to China was fired in March for alleged security violations at Los Alamos National Laboratory in New Mexico, lawmakers sought even tougher scrutiny.
Buried in the defense authorization act for fiscal 2000 is a provision that would make last year's law retroactive. It would require record keepers to re-inspect documents declassified since the executive order took effect about three years ago.
"In a recent 140-page study of improperly released nuclear weapons data, the administration detailed numerous examples of key design information that was not intended to be released, but, in fact, was released," Kyl said. "We have to be careful not to continue to accidentally release sensitive nuclear weapons design data that countries like Iran and Iraq could use to advance their own nuclear weapons programs."
Already approved by a House-Senate conference committee, Congress is to vote on the bill after its summer recess.
National Security Council spokesman David Leavy would not disclose the administration's reaction to the provision, except to say: "We have to be reasonable while balancing national security concerns." He also would not speculate on whether Clinton would sign the bill.