The most famous example of the "first hundred days," the one that turned it into a critical measure of success for subsequent presidents, was FDR's first term in 1933. FDR won an absolutely crushing electoral victory in 1932 that swept absolutely massive Democratic majorities into both houses of Congress, and FDR pledged that unlike Hoover, he would do something about the Depression. In the campaign, he hadn't been very clear as to what that "something" was, but upon taking office, he launched a sweeping set of reforms unlike anything ever seen before.

On his first day in office, he mandated a three day banking holiday to prevent runs on the bank, and over those days he and Congress passed a banking insurance scheme, the FDIC, to insure the deposits of Americans in their bank accounts so people wouldn't lose money if a bank went under. He launched the Civilian Conservation Corps, putting many Americans to work on environmental projects in the national parks. He created FERA, the Federal Emergency Relief Administration, which distributed aid to poor people in need. He created the Agricultural Adjustment Administration, which started paying farmers to not grow crops in order to prevent a surplus driving crop prices down. He created the Tennessee Valley Authority to electrify the American South for the first time. He created the Public Works Administration to put millions to work on public works projects like building government buildings, roads, bridges, and infrastructure, and created the National Recovery Administration, or NRA, an effort to harmonize labor and capital interests and end destructive competition.

This was all accomplished in three months.