President Biden has selected his education secretary, Miguel Cardona, to be the so-called designated survivor during Thursday night’s State of the Union address, a grim moniker meant to ensure at least one decision maker survives if a calamity were to wipe out the nation’s leadership assembled at the Capitol for the speech.

Secretary Cardona will follow the evening’s proceedings from an undisclosed location, becoming the latest member of a tradition that dates back to the Cold War tensions of the 1950s. The first survivor to be publicly disclosed was Terrel Bell, who served as education secretary to Ronald Reagan, in 1981.

There are few moments in American life when so many of the country’s top leaders are gathered in one place. Those gathered in the House chamber on Thursday will include many members of the Supreme Court, most of Mr. Biden’s cabinet, a great number of lawmakers and top military officials.

Those attending are in line to become president if something were to happen to Mr. Biden, as established by the Presidential Succession Act of 1947: the vice president, the speaker of the House, the president pro tempore of the Senate, the secretary of state, the secretary of the Treasury, the secretary of defense and the attorney general. (Beyond that, the succession proceeds through the rest of the cabinet.)

But that line of succession could be disrupted if there were an attack or disaster at the Capitol, which is why one cabinet member is chosen to skip the event.

Commerce Secretary Gina Raimondo was chosen as Mr. Biden’s designated survivor during his State of the Union speech in 2022. Marty Walsh, who was secretary of labor in 2023, was the survivor last year.

Mr. Biden did not select a designated survivor for his joint address to Congress in 2021. The speech was much more sparsely attended because of Covid, and most members of the cabinet and other top officials were watching from remote locations anyway.

William J Burns, the C.I.A. director who was made a member of the cabinet last July, will also not be at the State of the Union. Mr. Burns, according to a U.S. official, was in Doha, Qatar on Thursday, meeting with Qatari officials, as part of an effort to push forward talks on a temporary ceasefire and hostage release in Gaza.

Because Mr. Burns will not be in the secure location away from Washington, he will not be the official designated survivor. But since he will be away from the Capitol building, in the event of a catastrophe, he could be considered, unofficially, a second backup survivor.