The muckrakers were reform-minded journalists, writers, and photographers in the Progressive Era in the United States (1890s–1920s) who claimed to expose corruption and wrongdoing in established institutions, often through sensationalist publications. The modern term generally references investigative journalism or watchdog journalism; investigative journalists in the US are occasionally called "muckrakers" informally.

The Progressive Era (1896–1917) was a period in the United States during the early 20th century of widespread social activism and political reform across the country. Progressives sought to address the problems caused by rapid industrialization, urbanization, immigration, and political corruption as well as the enormous concentration of industrial ownership in monopolies. Progressive reformers were alarmed by the spread of slums, poverty, and the exploitation of labor. Multiple overlapping progressive movements fought perceived social, political, and economic ills by advancing democracy, scientific methods, and professionalism; regulating business; protecting the natural environment; and improving working and living conditions of the urban poor.