Ida Tarbell (1857–1944) was an investigative journalist who, in The History of the Standard Oil Company, a 1904 exposé published in McClure’s Magazine, brought to light the questionable legal maneuverings and business practices of the Standard Oil Company.
Jacob Riis (1849–1914) was a New York journalist and reformer. In 1890, Riis published How the Other Half Lives: Studies among the Tenements of New York, an exposé describing the terrible living conditions in New York City’s poorest neighborhoods. The successful book inspired public outcry for urban reforms.
John Muir (1838–1914) was a wilderness preservationist whose influence helped lead to the establishment of national parks. Muir was also a founder of the Sierra Club, which was formed in 1892 to preserve the Sierra Nevada wilderness.