AP Photos What's the designated survivor?

At every year’s State of the Union address, one cabinet official known as the “designated survivor” is asked to sit out the speech and watch from a distant location. While this year’s hasn’t yet been announced, here are some things to keep in mind when you find out who’s missing from Tuesday’s speech:

1. Who and Why? A designated survivor is a cabinet-level official appointed during the State of the Union every year in order to maintain the continuity of government should a “calamity” happen while all other members of the federal government are in a single location.


2. Line of succession: According to the detailed line of succession, the vice president takes over if something happens to the president, followed by: the Speaker of the House; the president pro tempore of the Senate; the Secretary of State; the Treasury Secretary; the Defense secretary; the Attorney General; and all the way down the line of cabinet officials. The designated survivor takes over if all parties in that line are wiped out.

( PHOTOS: The designated survivor from SOTU)

3. Presidential Security: The designated official is given presidential level security in an undisclosed location for the night. A military aide also accompanies the cabinet official, equipped with a briefcase containing the nuclear war plan.

4. Cold War Concerns: Presidential succession and government continuity emerged as a huge concern in the Cold War era, when the possibility of a devastating nuclear attack against Americans hovered uncomfortably over the U.S. government.

5. Tradition: The practice of appointing a designated survivor during State of the Union addresses dates back to (at least) the 1960s. The selection of the designated survivor was not customarily made public until the 1980s.

( WATCH: POLITICO’s issue-by-issue SOTU preview)

6. Mini Legislature: Since 2003, Members of Congress from each chamber have also been asked to sit out the State of the Union speech to maintain legislative succession.

7. Secrecy: Each year’s designated survivor must keep their selection under wraps until the night of the speech.

8. Inaugurations: State of the Union addresses aren’t the only occasion in which designated survivors are used. During President Obama’s inauguration in 2009, the outgoing Bush administration and the incoming Obama administration agreed to name then-Secretary of Defense Robert Gates the designated survivor. Veterans Affairs Secretary Eric Shinseki was the designated survivor for last year’s inauguration.

9. She’s a survivor: In 2010, both Hillary Clinton, then Secretary of State, and Housing and Urban Development Secretary Shaun Donovan missed the SOTU. Although Donovan was the official designated survivor, Clinton would have been next in the presidential line of succession.

10. Last year: The designated survivor in 2013 was Energy Secretary Steven Chu.