Progressive Era
What was it?
The Progressive Era (~1900-1916) marked a revolution in United States history. The end of the Civil War brought the beginning of a time known as the Gilded Age, a period marked by rampant corruption in government at all levels, a near complete social stagnation, as well as a near absence of any kind of business regulation (which led to, as one would imagine, predatory business and ethical practices). According to Isaac Newton, for every action, there is an equal and opposite reaction, as was the case with the sudden shift from the Gilded Age to the Progressive Era. In reaction to the rampant corruption, a variety of reforms were enacted. These included the direct election of senators (previously elected by state legislatures), the initiative (in which citizens could bypass their state legislatures and directly enact legislation), the referendum (in which citizens could vote directly on matters of importance), and the recall (in which citizens could vote out a corrupt or otherwise undesirable politician). In response to the social stagnation, prohibition as enacted, women were given the right to vote, and, as a consequence of wartime mobilization, women and minorities were given more economic opportunities. And in response to unethical business practices, a number of regulations were placed. These included the process of “trust-busting,” (in which monopolies were broken up into smaller businesses), the Federal Trade Commission (which prevented anti-competitive and unethical business practices), and the Federal Reserve (which set up a stable, nationalized financial system in order to make the economy more flexible). The Progressive Era is generally seen as having ended with the onset of World War I, but certain issues, especially social ones, were extended past that period.
Why's it important?
Because (most of) its programs and reforms still exist today. Americans still directly elect senators, and still have the right to initiative, referendum, and recall. Businesses are still regulated against unfair and anti-competitive business practices. The Federal Reserve still exists today (look at a dollar bill). Women can still vote. Women and minorities (now) have almost equal economic opportunities. The Progressive Era, most of all, set the stage for a mass liberalization of America. This process would be extended by the New Deal, and after the hiccup of the Red Scare, would push forward into the Great Society and Civil Rights Movement. It would only be the conservative resurgence of the 1970s and 1980s that would stop the ball that the Progressive Era began to roll.