L. Mencken, who will champion Dreiser’s writing throughout his career, begin to correspond.

1909   Dreiser and Sara separate. Guglielmo Marconi of Italy and Ferdinand Braun of Germany win the Nobel Prize in Physics for wireless telegraphy. The National Association for the Advancement of Colored People is founded, establishing its home office in New York City. 
1910   A romance with the seventeen-year-old daughter of one of his associates forces Dreiser’s resignation as Butterick’s editor. In New York City the Manhattan Bridge opens. Emma Goldman’s book Anarchism and Other Essays  appears.
1911  Jennie Gerhardt  is published to critical praise and support for its author. Marie Curie is awarded the Nobel Prize in Chemistry. Standard Oil’s largest remaining company is dissolved by the Supreme Court. In Manhattan the Triangle Shirtwaist Company sweatshop catches fire, killing 146 young immigrant workers.
1912  The Financier, the first of the “Trilogy of Desire” series about a ruthless American tycoon (based on transportation magnate Charles T. Yerkes), is published. After years of unhappiness, Dreiser and his wife permanently separate. The Titanic  sinks after striking an iceberg on her maiden voyage, killing 1,500 people.
1913   “On the Banks of the Wabash, Far Away,” a popular song written by Dreiser’s older brother Paul, is adopted as the state song of Indiana. Dreiser publishes A Traveler at Forty, a travelogue of his journey to Europe. Carl Jung publishes The Theory of Psychoanalysis. 
1914   World War I breaks out in Europe. The second “Trilogy of Desire” installment, The Titan, is published. American novelist Booth Tarkington publishes Penrod. 
1915   Dreiser publishes The “Genius,”  a semi-autobiographical novel. It is censured by the New York Society for the Suppression of Vice and removed from bookshelves. Albert Einstein introduces his General Theory of Relativity.
1916   Dreiser’s memoir A Hoosier Holiday is published, as well as Plays of the Natural and Supernatural. Carl Sandburg publishes Chicago Poems.  Nine days after Margaret Sanger opens the nation’s first birth-control clinic in Brooklyn, she is arrested and the clinic is shut down.
1917   The United States enters World War I. Poet T. S. Eliot publishes Prufrock and Other Observations. The Bolshevik Revolution in Russia topples the czar and installs V. I. Lenin as the first head of the Soviet state. H. L. Mencken publishes A Book of Prefaces,  a collection of literary essays that includes a positive assessment of Dreiser.
1918   Dreiser publishes Free and Other Stories and the novel The Hand of the Potter, whose central character is a child molester. H. L. Mencken publishes In Defense of  Women.
1919   World War I ends. Twelve Men, Dreiser’s collection of fictional biographical portraits, appears.