Answer: Upton Sinclair’s February 1906 novel The Jungle, an exposé of the Chicago meatpacking industry.
Upton Sinclair, one of the most prominent writers later derided as “muckrakers” by Theodore Roosevelt, was born on September 20, 1878 in Baltimore, Maryland.
Read a brief biography from C-Span’s “American Writers” series.
According to the Food and Drug Administration’s official website:
In fact, the nauseating condition of the meat-packing industry that Upton Sinclair captured in The Jungle was the final precipitating force behind both a meat inspection law and a comprehensive food and drug law.
The law was passed in June 1906 and signed by President Theodore Roosevelt.
Read more about the “muckrakers” in the Progressive Era in Don’t Know Much About® History.