Upton Sinclair's The Jungle aimed to draw attention to the exploitation and suffering inflicted on the American working class. However, with that being said, the novel's most enduring legacy lay in its depiction of American meatpacking and the political repercussions of that depiction.
Sinclair's picture repulsed and horrified readers, as it described (in gruesome detail) the unsanitary conditions of the meatpacking industry and the degree to which the meat that was sold to American consumers was contaminated by those conditions. The result was to capture public attention, as it raised serious anxieties throughout the American population concerning the quality of the meat they might have been consuming.
President Theodore Roosevelt ordered an investigation to look into Sinclair's claims and determine the accuracy of his depiction. Its results had the effect of confirming Sinclair's picture. One can thus draw a direct link between The Jungle and the successful passage of the Pure Food and Drug Act and the Meat Inspection Act.
Sinclair's novel raised public awareness to these abuses, and its visceral manner of presentation caused readers to react in revulsion. When those claims were confirmed by government inquiry, regulation became necessitated, given the stakes and implications for public health and welfare. Thus, Upton Sinclair's work in The Jungle had a significant role in shaping the passage of later legislation.