Did the United States have a hand in assassinating Congolese and Dominican leaders in 1961? What did President Richard Nixon’s White House know about a successful plot to kill the head of the Chilean army in 1970? After the Cold War ended, did top U.S. military commanders retain the authority to strike back if a surprise nuclear attack put the president out of commission? The answers to these and other historical mysteries are likely knowable—but they are locked in presidential libraries and government archives and inaccessible to researchers. The reason: the U.S. government’s system for declassifying and processing historical records has reached a state of crisis.