Upton Sinclair started publishing "dime novels" in 1893 when he was 15. By the time he died at 90, he was credited with writing more than 100 books, plays and pamphlets.

Even though his novel "Dragon's Teeth" won the 1943 Pulitzer Prize, only one Sinclair book is read regularly today -- "The Jungle."

The novel, with its tear-jerker plot and simplistic political message, appeared in 1906, with Sinclair paying for the printing. (Self-published writers, take note.)

The memorable scenes were at Chicago's stockyards, a place Sinclair first wrote about as a muckraker for a socialist publication. There he found both dangerous working conditions and deplorable sanitation.

The book's impact was explosive. It even reached the White House, where President Theodore Roosevelt was so moved that he launched the campaign that would lead to regulations protecting the nation's food supply.

"The Jungle" still carries a wallop today. Eric Schlosser, another journalist, whose book "Fast Food Nation" opened plenty of eyes and upset a few stomachs, has taken up the same cause as Sinclair after reading his novel.

At the Heinz Lectures last week, Schlosser used the book to decry the current state of the American meat-packing industry.

He claims that the picture is even bleaker than in Sinclair's day, thanks to dominance by a few giant companies who use migrant and illegal workers to handle the dangerous work at low pay and no benefits.

Schlosser concluded his talk by urging a citizens' campaign to reform the business.

"The Jungle," then, is a novel that made a difference. Its overheated melodrama stirred enough outrage to affect change on a national scale, beginning the growth of government regulation.

I can't think of any other American novel with such far-reaching social impact. "Uncle Tom's Cabin," equally as melodramatic, revealed the inhumanity of slavery to Northerners and swayed hearts and minds but not in such specific fashion as "The Jungle."

Sinclair was writing at a time when Americans were becoming familiar with a steady stream of attacks on their society. The muckrakers, a label taken from Roosevelt's criticism of journalists, were exposing the misdeeds of big business and local government on a monthly basis.

Ida M. Tarbell's "The History of the Standard Oil Company," Lincoln Steffens' "The Shame of the Cities," the sociological reports of Jacob Riis on New York tenements, the photos of Lewis Hine and the efforts of Jane Addams at Chicago's Hull House brought home the message that industrial society bred problems.

When novelists like Stephen Crane ("Maggie: A Girl of the Streets") and Theodore Dreiser ("Sister Carrie") turned society's ills into fiction, the message became more dramatic and emotional than straightforward journalism.

It's important to note that Crane and Dreiser -- like Sinclair -- started in journalism, with Dreiser spending a few years on a Pittsburgh newspaper. That experience fueled the rise of what literary critics term the naturalistic movement in American fiction, a change from the novels of manners written by Henry James, Edith Wharton and William Dean Howells at the end of the 1800s.

Life in the drawing room was tame stuff after a tour of blast furnaces, brothels and stockyards.

"The Jungle" is a product of the progressive era, a reform movement that even reached the patrician Teddy, who moved further and further to the left as abuses and scandals came to light. It would be one of kind. Thirty-three years later, John Steinbeck's "The Grapes of Wrath" defined another American tragedy, the displacement of the Dust Bowl, but its impact never approached that of "The Jungle."

The American novel moved on, turning more and more inward, focusing on individuals instead of the larger society. By the 1950s, Richard Yates' "Revolutionary Road" and Sloan Wilson's "The Man in the Gray Flannel Suit" revealed the emptiness of the American corporate world while John Cheever and John Updike's stories found the suburbs sterile, but these were not issues that laws or policies could change.

Little has changed. Today's fiction, from Philip Roth's "The Plot Against America" to Cormac McCarthy's "No Country for Old Men," involves personal struggles in a dangerous world.

As for Upton Sinclair, he continued to try to change conditions for workers, running -- and losing -- twice for governor of California in the 1930s on socialist platforms.

He then returned to fiction, writing the 11-book Lanny Budd adventure series about a dashing American agent fighting his nation's enemies.

None of them, it seems, owned a meat-packing company.