The idea of the President's first 100 days in office being a measure of success dates to 1933. Taking office as President in that year was Franklin D. Roosevelt, who had defeated incumbent Herbert Hoover in a landslide in the Election of 1932.

The United States and much of the world were in the depths of the Great Depression. A great many people were out of work, out of money, and out of hope. Roosevelt sought to provide all three, with a series of legislative measures that found favor with Congress, which happened to be controlled by the Democratic Party, to which Roosevelt also belonged.

In a July 24, 1933 radio address, Roosevelt spoke of the first 100 days of the 1933 Congressional session. Roosevelt had been inaugurated on March 4, and Congress had opened for business on March 9, after the Roosevelt-induced "bank holiday" and a few other emergency measures designed to restore Americans' confidence in Government.

The 100th day of the Congressional session was June 17 that year. By that time, Congress had passed and Roosevelt had signed 76 bills. More than a dozen were major pieces of legislation, cornerstones of Roosevelt's New Deal; other laws were smaller in scope.

That total of 76 was far and away the highest number of new laws enacted by a President and a Congress in modern times. Following in Roosevelt's footsteps, literally, was President Harry Truman, who assumed the Presidency when Roosevelt died. (Truman had been Vice-president.) Truman won the Election of 1948, along with a Democratic majority, and he and that year's Congress passed 55 bills into law in their first 100 days in office.

After 76 and 55, third in the list is a much lower number, primarily because modern lawmaking involves not only committees but also subcommittees and, at times, exhaustive debate inside and outside congressional discussion on the bills before the two houses. The third-highest number of laws passed in the first 100 days of a President's term is 28, in 2017, the year that Donald Trump took office. He enjoyed a majority of his fellow Republicans in both the Senate and the House of Representative.

John F. Kennedy enjoyed similar majorities in 1963; in the first 100 days of Kennedy's presidency, he signed 26 bills into law. That figure was tfour higher than Bill Clinton and six higher than Dwight D. Eisenhower (1953) and Jimmy Carter (1977).

For the rest of the Presidents since Franklin Roosevelt:

President	1st year in office	Bills passed
George Bush	1989	18
Lyndon Johnson	1965	18
Barack Obama	2009	14
Joe Biden	2021	11
Richard Nixon	1969	9
Ronald Reagan	1981	9
George W. Bush	2001	7