Sister Carrie by Theodore Dreiser

According to Wikipedia: Theodore Herman Albert Dreiser (August 27, 1871 – December 28, 1945) was an American novelist and journalist. He pioneered the naturalist school and is known for portraying characters whose value lies not in their moral code, but in their persistence against all obstacles, and literary situations that more closely resemble studies of nature than tales of choice and agency... His second novel, Jennie Gerhardt, was published in 1911. Many of Dreisers subsequent novels dealt with social inequality. His first commercial success was An American Tragedy (1925), which was made into a film in 1931 and again in 1951.