As the twentieth century opened, Americans were jolted out of their laissez-faire complacency by detailed exposures, in journalism and fiction, of the corruption underlying the country's greatest institutions. This rude awakening was the work of the muckrakers, as Theodore Roosevelt christened these press agents for reform.   From 1902, when it latched onto such mass circulation magazines as Collier's and McClure's, until it merged into the Progressive movement in 1912, muckraking relentlessly pricked the nation's social conscience by exposing the abuses of industry and politics. Ranging in tone from the scholarly to the sensational, muckraking articles attacked food adulteration, unscrupulous insurance practices, fraudulent claims for patent medicines, and links between government and vice. When muckrakers raised their voices against child labor, graft, monopoly, unsafe mill conditions, and the white slave trade of poor immigrant girls, they found a receptive audience. "I aimed at the public's heart," wrote Upton Sinclair about The Jungle, "and by accident I hit it in the stomach."   Gathering the most significant pieces published during the heyday of the muckraking movement, The Muckrakers brings vividly to life this unique era of exposure and self-examination. For each article, Arthur and Lila Weinberg provide concise commentary on the background of its subject and the specific and long-range repercussions of its publication. The volume features the work of both journalists and fiction writers, including Ida Tarbell, Lincoln Steffens, Upton Sinclair, Ray Stannard Baker, Samuel Hopkins Adams, Thomas W. Lawson, Charles Edward Russell, and Mark Sullivan.   Eloquent and uncompromising, the muckrakers shocked America from a state of lethargy into Progressive reform. This generous volume vividly captures the urgency of their quest.