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.
List of Presidents of the United States by time in office
William Henry Harrison spent the shortest time in office, and Franklin D. Roosevelt spent the longest. Roosevelt is the only president to have served more than two terms. Following ratification of the Twenty-second Amendment in 1951, presidents—beginning with Dwight D. Eisenhower—have been ineligible for election to a third term or for election to a second full term after serving more than two years of a term to which some other person was elected president. The amendment contained a grandfather clause that explicitly exempted the incumbent president, then Harry S. Truman, from the new term limitations, which first applied to Dwight D. Eisenhower.