Between 1841 and 1975, more than a third of U.S. presidencies ended abruptly because of death, resignation or disability. But even with the leader of the free world gone, the country never descended into anarchy. How'd we pull that off?

Well, there's this nifty little thing called the line of presidential succession, which lays out who steps up to become, or act as, President upon the death, resignation, removal or incapacitation of a sitting president or president-elect.

How does it work? And does it work? Let's start at the beginning"¦

The Law of the Line

Succession law begins with the Presidential Succession Act of 1792, which declared that should the office of the president become vacant, the VP, the President pro tempore of the Senate and the Speaker of the House would be in line to act as president until a special election could be held to fill the office.

When President Garfield (pictured) was assassinated in 1881, there was no President pro tempore or Speaker of the House in office, which left no line after the vice president. To guard against future situations like that, President Cleveland asked Congress to revise the Succession Act in 1885. The new act was passed a year later, with the officers of the President's Cabinet replacing the President pro tempore and Speaker of the House in the order in which the cabinet offices were established.

The order of the line changed once more with another succession act in 1947. The President pro tempore and Speaker of the House were added back to the line ahead of the cabinet officers, but with their positions from the 1792 act switched.

The line has stayed the same since 1947, but one more piece of important succession legislation came in 1967. The 25th Amendment clarified some ambiguous succession language in the Constitution and set a procedure for filling a vacant vice president's office. Prior to the amendment, if the VP died, resigned or succeeded the president, their office remained vacant (in fact, the country has gone a total of 37 years without a VP). The amendment established that the president would nominate a new VP, who would then be confirmed by a majority vote in Congress.

If something were to happen to the President today"¦

The current line of succession is:

The Vice President - Dick Cheney

Speaker of the House - Nancy Pelosi

President pro tempore of the Senate - Â Robert Byrd

Secretary of State - Condoleezza Rice

Secretary of the Treasury - Henry Paulson

Secretary of Defense - Robert Gates

Attorney General - Michael Mukasey

Secretary of the Interior - Dirk Kempthorne

Secretary of Agriculture - Edward T. Schafer

Secretary of Commerce - Carlos Gutierrez

Secretary of Labor - Elaine Chao

Secretary of Health and Human Services - Mike Leavitt

Secretary of Housing and Urban Development - Steven C. Preston

Secretary of Transportation - Mary E. Peters

Secretary of Energy - Samuel Bodman

Secretary of Education - Margaret Spellings

Secretary of Veterans Affairs - James Peake

Secretary of Homeland Security - Michael Chertoff

There are a few catches here. One, every person in the line has to meet the eligibility requirements of the presidency to step into the position. Both Secretary Gutierrez and Secretary Chao are ineligible because they were born in Cuba and Taiwan, respectively. Likewise, any member of the cabinet who is under 35 or hasn't resided in the U.S. for 14 years is ineligible to become president. Two, some members of the cabinet, like the White House Chief of Staff, are not in the line of succession. Only secretaries of departments in the executive branch are included.

The End of the Line

What if the excrement hits the air-conditioning, though, and everyone in the line is unable to assume the presidency? None of the current succession laws say anything about it. Instead, the government is just very careful about keeping everyone in the line from being in the same place at the same time. For events that all persons in the line usually attend "“ the State of the Union address, joint sessions of Congress, presidential inaugurations "“ one member of the cabinet eligible for the presidency is selected as the designated survivor and hidden in an undisclosed location for the duration of the event. In case disaster strikes, the designated survivor will be able to take charge.

Bonus Succession Trivia

Presidents Arthur, Coolidge, Fillmore, Ford, Andrew Johnson, Lyndon Johnson, Theodore Roosevelt, Truman and Tyler all became president by succession.

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When President Arthur traveled, he left an envelope at the White House addressed simply to "The President." If something happened to him, he assumed the right person would open it.

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Gerald Ford has to be the man who benefited most from the line of succession. Nixon's vice president, Sprio Agnew, resigned after the 25th Amendment was ratified. President Nixon nominated Ford to fill the spot. Not long after that, Nixon resigned, and Ford took another step up the ladder. The system works!

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For a period of time, the Postmaster General was the senior officer of the Post Office Department "“ a part of the cabinet "“ and the last person in the line of succession. In 1971, the Post Office Department became the U.S. Postal Service and the Postmaster General was removed from both the cabinet and the line.

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The line of succession has a few kinks in it. For one thing, the Constitution doesn't allow members of the legislative branch to also serve in the executive branch (what with the separation of powers and all). If the Speaker of the House or the President pro tempore had to assume the presidency, they would first need to resign from their current position, which means they would be out of the line. If you're a stickler for details, this could be a bit of a paradox.

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Succession law also doesn't provide any direction for a situation where a former president ineligible to serve another term is in the line of succession (if they don't close that loophole, it's a great way for Slick Willy to sneak back into office).

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Of course, the kinks haven't been a problem, since no officer beyond the vice president has ever been called upon to become, or act as, President.

If you've got a burning question that you'd like to see answered here, shoot me an email at flossymatt (at) gmail.com. Twitter users can also make nice with me and ask me questions there. Be sure to give me your name and location (and a link, if you want) so I can give you a little shout out.