I nominate
Sister Carrie by Theodore Dreiser.
From Goodreads:
Dreiser's unsparing story of a country girl's rise to riches as the mistress of a wealthy man marked the beginning of the naturalist movement in America. Both its subject matter and Dreiser's objective, nonmoralizing approach made it highly controversial, and only a heavily edited version could be published in 1900.
Available free from:
MR Library (lrf) -
Amazon -
Kobo