The Twentieth Amendment

Section 1.

"The terms of the President and Vice President shall end at noon on the 20th day of January, and the terms of Senators and Representatives at noon on the 3d day of January, of the years in which such terms would have ended if this article had not been ratified; and the terms of their successors shall then begin."

Section 2.

"The Congress shall assemble at least once in every year, and such meeting shall begin at noon on the 3d day of January, unless they shall by law appoint a different day."

Section 3.

"If, at the time fixed for the beginning of the term of the President, the President elect shall have died, the Vice President elect shall become President. If a President shall not have been chosen before the time fixed for the beginning of his term, or if the President elect shall have failed to qualify, then the Vice President elect shall act as President until a President shall have qualified; and the Congress may by law provide for the case wherein neither a President elect nor a Vice President elect shall have qualified, declaring who shall then act as President, or the manner in which one who is to act shall be selected, and such person shall act accordingly until a President or Vice President shall have qualified.”

Section 4.

"The Congress may by law provide for the case of the death of any of the persons from whom the House of Representatives may choose a President whenever the right of choice shall have devolved upon them, and for the case of the death of any of the persons from whom the Senate may choose a Vice President whenever the right of choice shall have devolved upon them."

Section 5.

"Sections 1 and 2 shall take effect on the 15th day of October following the ratification of this article."

Section 6.

"This article shall be inoperative unless it shall have been ratified as an amendment to the Constitution by the legislatures of three-fourths of the several states within seven years from the date of its submission."

Section 1.

After an election year, the President and vice president's terms will end on January 20th, and Congressmen will end their terms on January 3rd.

Section 2.

Congress begins every new term on January 3rd, unless they pass a law that says otherwise.

Section 3.

If the President is no longer able to serve their term, the Vice President is next in line. The Vice President can have temporary Presidential authority if the President is unable to fulfill the duties of the office.

Section 4.

In the case of death of anyone in the Electoral College prevents them from electing a President, Congress may choose.

Section 5.

Self explanatory.

Section 6.

This amendment needs a 3/4 acceptance vote from the states within 7 years to be ratified. 

To be honest, I just learned what a lame duck is. The original definition is an ineffectual or unsuccessful person or thing. In American politics, a lame duck is a political official in their final period of office, after the election of their successor. This cartoon represents the impending doom of Donald Trump following the presidency of Barack Obama. 

Before this amendment was passed, the President and Vice President took over office on March 3rd of the following year, but they decided to move the date up to January 20th. At the end of 1932, FDR was elected President and many banks were collapsing due to the Great Depression. Current President Herbert Hoover was the sitting "lame duck" who had little ability to take action on the banking crisis, and FDR still had a few months to wait. It was decided that moving the term starting date up to January would be beneficial that year and in the future. 

The reason the 20th amendment determined who would take over office if the President died is because of the assassination attempt of FDR in 1933. It happened on February 15th, in Miami, Florida, when Roosevelt was not yet in office but was the president-elect. The man who shot at FDR and four others was Giuseppe (Joe) Zangara, who successfully shot Anton Cermak, the mayor of Chicago. Cermak died 19 days later. Roosevelt was unharmed although he may have been the intended target.