- *The Jungle* (1906): This novel exposed the unsanitary and unsafe conditions in the meatpacking industry in the United States. It led to the passage of the Pure Food and Drug Act of 1906.
2. Ida Tarbell:
- *The History of the Standard Oil Company* (1904): This two-volume work documented the rise of the Standard Oil Company and how it used its monopoly power to crush its competitors. It helped spur the breakup of the company by the U.S. Supreme Court in 1911.
3. Lincoln Steffens:
- *The Shame of the Cities* (1904): This book exposed the corruption and political graft that were rampant in many American cities at the turn of the 20th century. It led to several municipal reforms, including the adoption of commission and city manager forms of government.
4. David Graham Phillips:
- *The Treason of the Senate* (1906): This book accused many U.S. Senators of being corrupt and beholden to special interests. It led to several investigations and resignations, but Phillips was assassinated in 1911 before he could complete a second volume.