美农业部长担任“指定幸存者”

Agriculture Secretary Sonny Perdue has been named the "designated survivor" during the State of the Union speech by U.S. President Donald Trump.

Each year, one member of the president's Cabinet is whisked away to an undisclosed location during the address in case a catastrophic event occurs and wipes out the line of presidential succession.

The tradition harkens back to the dawn of the Cold War, amid fears of a nuclear exchange with the Soviet Union.

After the vice president, the speaker of the House, and the president pro tempore of the Senate, the line of succession goes to Cabinet secretaries in the order they were created, beginning with the Secretary of State and ending with the Secretary of Homeland Security.

One member of Trump's Cabinet cannot serve as a designated survivor: Secretary of Transportation Elaine Chao, who was born in Taiwan and does not meet the constitutional requirements to serve as president.

The designated survivor will take over duties as the acting commander-in-chief is case of a catastrophic event.