George Washington
At the end of his second term, Washington retired for personal and political reasons, fatigued and disgusted with personal attacks, and to assure a truly contested presidential election could be held. He did not feel bound to a two-term limit, but his retirement ultimately set precedent. The two-term limit to the presidency was formalized with the 1951 adoption of the Twenty-second Amendment to the United States Constitution. Washington is often credited with setting the principal of a two-term presidency, but it was Thomas Jefferson who first refused to run for a third term on political grounds.
Presidency of Herbert Hoover
Efforts to change these dates through a constitutional amendment began in the late 1920s. In March 1932, Congress approved a constitutional amendment moving the beginning and ending of the terms of the president and vice president from March 4 to January 20, and of members of Congress from March 4 to January 3. The amendment also specified procedures for cases in which the president-elect dies or otherwise fails to qualify. By January 23, 1933, the amendment had been ratified by the requisite number of states to become the Twentieth Amendment. Roosevelt's second inauguration in 1937 was the first presidential inauguration to take place on the new date.