A short list.
Muckrakers– named by Theodore Roosevelt while in the midst of an elephant hunt, these investigative journalists dug up dirt on corruption and other ills of society. A famous muckraker was Upton Sinclair. He caused a whole generation to go vegetarian.
Ida Tarbell– Known to have raked the most muck in her day. Mainly became famous from her writings about the corruption within Standard Oil. She said something like, “Hey, Standard Oil. You know how your name is Standard Oil. Well you are in fact operating under a SUB-standard format. So stop, please.” She was quite the orator.
Salvation Army– A large army that was deployed into the United States to fight the war on poverty, the longest lasting American war to date.
Robert La Follette– Popular governor of Wisconsin. Could have possibly won the Republican nomination for president once, but he blew it by crying in front of a crowd. He never lived it down.
Jane Addams– Born into the Addams family. Was the founder of Hull House. She helped many immigrants, but her efforts could never reach everyone, as they just wouldn’t stop coming. Hull House provided a PLETHORA of services if you know what I mean.
suffrage– Women and blacks were all like, “we want the right to vote”, so they fought for it, and with enough persistence (women can be very persuasive), they got it. Hats off to them.