In 1900, Sinclair left his graduate program to write a poetic novel, and later that year married Meta Fuller. This novel, Springtime and Harvest (later published as King Midas) was published a year later, the same year his first son, David was born. During the next three years, he continued writing pulp fiction and worked as a journalist to support his family. These jobs, combined with his interest in socialism, conflicted with his desire to be a poet. Sinclair wanted to use words and language to express universal ideals and truths, but instead he found himself using words and language to amuse, entertain, and pay the bills. He recognized that the life of a poet was not always the life of practicality, but having a wife and son to support, Sinclair needed to be practical and abandoned the life of a poet.
The editor of Appeal to Reason, Fred D. Warren, read Manassas (1904), Sinclair's third novel, and commissioned Sinclair to write about the conditions of the Chicago stockyards for the Appeal, a weekly socialist newspaper. After accepting the assignment, Sinclair lived in Chicago for nearly two months, studying the people and the working conditions of the industrial town. His observations became The Jungle, his next serious novel. After being published as a series in the Appeal, it took the work and financing of fellow socialist and author Jack London to get privately bound versions of the text printed. While Sinclair was publishing his book privately, five publishers rejected it based on content. Some wanted to print the book, provided that Sinclair delete some inflammatory and offensive passages. He refused. Eventually, Doubleday, Page and Company agreed to publish it, after verifying the basic truth of his allegations.
Throughout his career, Sinclair continued to write literature that depicted social issues: Oil! (1927) focused on the illegal leasing of oil reserves known as the Teapot Dome scandal and The Brass Check (1919) is a fictional account of his demonstration and subsequent arrest for speaking out against the 1914 coal mine strike. The extent of the prestige that Sinclair enjoyed during his lifetime is revealed in his 1960 collection of correspondence, My Lifetime in Letters. Included in the compilation are letters from Sinclair Lewis, Theodore Roosevelt, Jack London, H.L. Mencken, and Albert Einstein. Sinclair's career concluded with his final publication, The Autobiography of Upton Sinclair.
