In part due to George Washington's illness eighteen months earlier, on February 20, 1792 the United States Senate joined the House of Representatives in passing what is now commonly known as the "Presidential Succession Act of 1792," the first comprehensive law establishing a line of succession to the presidency.  Formally known as "An Act relative to the Election of a President and Vice President of the United States, and declaring the Officer who shall act as President in case of Vacancies in the office both of President and Vice President," the act deals with a variety of issues, waiting until Section 9 to address the subject for which it ultimately becomes known.

Section 9 provides that, if both offices (President and Vice President) are vacated, the President pro tempore of the United States Senate would "for the time being act as President of the United States until the disability be removed or a President shall be elected."  Next in line was the Speaker of the House of Representatives, but as you can read in the text of the act (below), it made no provision beyond the Speaker - a misnomer sometimes stated in resources on presidential succession law.

Perhaps the most fascinating thing about the 1792 law isn't the succession law (Section 9) itself, but what's contained in Sections 10 and 12.  In those sections, Congress provided that if both offices were vacated, a new election of a President and Vice President should be held - with the newly elected officers serving full, four year terms.  Section 10 reads in an unwieldly fashion and its provisions are perhaps best lost to history, but the thought of having a presidential election more frequently than every four years - now seemingly unconscionable - was apparently exactly what our nation's founding fathers intended had both the Presidency and Vice Presidency ever been simultaneously vacant.

Unfortunately, the 1792 law did nothing key questions which were raised during President Washington's 1790 illness:  How would a Vice President become Acting President if the President became disabled?  How would a President constitutionally resume his office... or, for that matter, could he even do so?  Despite a number of incidents during the near century under which the law was in effect, we'd thankfully not find out.

TEXT OF THE PRESIDENTIAL SUCCESSION ACT OF 1792

An Act relative to the Election of a President and Vice President of the United States, and declaring the Officer who shall act as President in case of Vacancies in the offices both of President and Vice President.

Section 1.  Be it enacted by the Senate and House of Representatives of the United States of America in Congress assembled, That except in case of an election of a President and Vice President of the United States, prior to the ordinary period as herein after specified, electors shall be appointed in each state for the election of a President and Vice President of the United States, within thirty-four days preceding the first Wednesday in December, one thousand seven hundred ninety-two, and within thirty-four days preceding the first Wednesday in December in every fourth year succeeding the last election, which electors shall be equal to the number of Senators and Representatives, to which the several states may by law be entitled at the time, when the President and Vice President, thus to be chosen, should come into office:  Provided, always, That where no apportionment of Representatives shall have been made after any enumeration, at the time of choosing electors, then the number of electors shall be according to the existing apportionment of Senators and Representatives.

Section 2.  And be it further enacted, That the electors shall meet and give their votes on the said first Wednesday in December, at such place in each state as shall be directed, by the legislature thereof; and the electors in each state shall make and sign three certificates of all the votes by them given, and shall seal up the same certifying on each that a list of the votes of such state for President and Vice President is contained therein, and shall by writing under their hands, or under the hands of a majority of them, appoint a person to take charge of and deliver to the President of the Senate, at the seat of government, before the first Wednesday in January then next ensuing, one of the said certificates, and the said electors shall forthwith forward by the post-office to the President of the Senate, at the seat of government, one other of the said certificates, and shall forthwith cause the other of the said certificates to be delivered to the judge of that district in which the said electors shall assemble.

Section 3.  And be it further enacted, That the executive authority of each state shall cause three lists of the names of the electors of such state to be made and certified and to be delivered to the electors on or before the said first Wednesday in December, and the said electors shall annex one of the said lists to each of the lists of their votes.

Section 4.  And be it further enacted, That if a list of votes, from any state, shall not have been received at the seat of government on the said first Wednesday in January, that then the Secretary of State shall send a special messenger to the district judge in whose custody such list shall have been lodged, who shall forthwith transmit the same to the seat of government.

Section 5.  And be it further enacted, That Congress shall be in session on the second Wednesday in February, one thousand seven hundred and ninety-three, and on the second Wednesday in February succeeding every meeting of the electors, and the said certificates, or so many of them as shall have been received, shall then be opened, the votes counted, and the persons who shall fill the offices of President and Vice President ascertained and declared, agreeably to the constitution.

Section 6.  And be it further enacted, That in case there shall be no President of the Senate at the seat of government on the arrival of the persons entrusted with the lists of the votes of the electors, then such persons shall deliver the lists of votes in their custody into the office of the Secretary of State, to be safely kept and delivered over as soon as may be, to the President of the Senate.

Section 7.  And be it further enacted, That the persons appointed by the electors to deliver the lists of votes to the President of the Senate, shall be allowed on the delivery of the said lists twenty-five cents for every mile of the estimated distance by the most usual road, from the place of meeting of the electors, to the seat of government of the United States.

Section 8.  And be it further enacted, That if any person appointed to deliver the votes of the electors to the President of the Senate, shall after accepting of his appointment neglect to perform the services required of him by this act, he shall forfeit the sum of one thousand dollars.

Section 9.  And be it further enacted, That in case of removal, death, resignation or inability both of the President and Vice President of the United States, the President of the Senate pro tempore, and in case there shall be no President of the Senate, then the Speaker of the House of Representatives, for the time being shall act as President of the United States until the disability be removed or a President shall be elected.

Section 10.  And be it further enacted, That whenever the offices of President and Vice President shall both become vacant, the Secretary of State shall forthwith cause a notification thereof to be made to the executive of every state, and shall also cause the same to be published in at least one of the newspapers printed in each state, specifying that electors of the President of the United States shall be appointed or chosen in the several states within thirty-four days preceding the first Wednesday in December then next ensuing:  Provided, There shall be the space of two months between the date of such notification and the said first Wednesday in December, but if there shall not be the space of two months between the date of such notification and the first Wednesday in December, and if the term for which the President and Vice President last in office were elected shall not expire on the third day of March next ensuing, then the Secretary of State shall specify in the notification that the electors shall be appointed or chosen within thirty-four days preceding the first Wednesday in December in the year next ensuing, within which time the electors shall accordingly be appointed or chosen, and the electors shall meet and give their votes on the said first Wednesday in December, and the proceedings and duties of the said electors and others shall be pursuant to the directions prescribed in this Act.

Section 11.  And be it further enacted, That the only evidence of a refusal to accept or of a resignation of the office of President or Vice President, shall be an instrument in writing declaring the same, and subscribed by the person refusing to accept or resigning, as the case may be, and delivered into the office of the Secretary of State.

Section 12.  And be it further enacted, That the term of four years for which a President and Vice President shall be elected shall in all cases commence on the fourth day of March next succeeding the day on which the votes of the electors shall have been given.