Constitutional FAQ Answer #9
Q9. "I know the order of power in the event of the death of the president is the V.P., then the speaker of the house. Where does it go from here?"
A. The Constitution actually only provides for the Vice President to succeed the President. The Constitution, in Article 2, Section 1 and Amendments 20 and 25, basically says that aside from the VP, the line of succession is by law. The exact order is in the U.S. Code, specifically 3 USC 19. Right now, the order is Speaker of the House, President Pro Tem of the Senate, then the members of the Cabinet (in the order the agencies were added).
This question has only been around since the cold war. Prior to the 25th Amendment, there was no procedure in place for replacing a vacant Vice Presidency, and, in fact, all Vice Presidents who succeeded a dead President served out the term without a VP; and each time a VP died, the President served without a backup. The Framers either never thought of the need for a double succession, or thought the odds that the VP who becomes president would then die were pretty slim. The 1792 Succession Act did provide for the Presidency to be taken by the President Pro Tem of the Senate, then by the Speaker of the House. In 1886, these individuals were replaced by the cabinet secretaries, and in 1947, the Congress placed the Speaker and President Pro Tem at the top of the order.
The 25th put the matter to rest — with the prospect of Washington D.C. being melted in a nuclear fire, and most of the legislative and executive branch turning to ash in a split second, the line of succession became more important.
See the Line of Succession Topic Page for even more information.