State of the Union attendees include the president, vice president, Cabinet, Congress, and Supreme Court. Any terrorist attack could wipe out the entire line of succession. Therefore, one Cabinet member is usually picked by the president to get a special invitation to not attend the State of the Union speech. For Tuesday’s State of the Union, the designated survivor was Energy Secretary Steven Chu.
The tradition of the “designated survivor” goes back to the 1950s, when the United States and the Soviet Union locked horns in a nuclear stalemate. The process was so secret that it wasn’t really acknowledged publicly by the government until the 1980s.The presidential line of succession is covered in both Article II, Section 1 of the Constitution, which was later amended and clarified by the 20th Amendment, and detailed in the Presidential Succession Act. To ensure the preservation of at least part of the succession, the survivor is taken to a safe location away from the event.
NPR says that in recent years, the lucky Cabinet member has stayed in Washington and ordered pizza while he or she sat with a security detail—along with the “nuclear football,” the famed briefcase with the nuclear launch codes.