- Ida Tarbell: Tarbell's investigative reporting, particularly her exposé of Standard Oil, was instrumental in bringing about trust-busting legislation.
- Lincoln Steffens: Steffens' muckraking journalism, which revealed corruption and political machines in cities like New York and Chicago, led to municipal reform movements and increased demands for transparency.
- Jacob Riis: Riis' photographs of poverty and poor living conditions helped spark the Progressive Era's focus on social welfare and urban planning.
- Ray Stannard Baker: Baker's journalistic work on issues such as child labor, women's rights, and immigration had a profound impact on public discourse and policymaking.
- William Allen White: White's editorials and political commentary were instrumental in shaping the political agenda and influencing public opinion in Kansas and beyond.
- Florence Kelley: Kelley combined journalism and activism to advocate for labor rights and social justice.
- Samuel Hopkins Adams: Adams' reporting exposed the dangers of food and drug adulteration, resulting in legislative action such as the Pure Food and Drug Act.
These journalists used various platforms, including newspapers, magazines, and books, to investigate and report on social and political issues, exposing corruption, advocating for reform, and providing critical information to the public. Their work collectively had an enormous impact on the formation of public opinion, the shaping of policy agendas, and the overall trajectory of the Progressive Era.