The peculiarity, poverty, and injustice in the Depression-era South was embedded in Erskine Caldwell's memory. His observations had little to do with remnants of "the late unpleasantness" - the polite Southern term for the Civil War. They had everything to do with being a "PK," a preacher's kid who moved with his family to a number of churches throughout the South before settling in Wrens, Georgia when he was fifteen. Still, his father preached on long circuits and was happy to have his son accompany him. Caldwell later wrote that his father traveled so regularly that he could determine the destinations by the odor of coal smoke on his suit.
On these travels Caldwell observed the raw realities of the human condition in the South. After he left the South in the late 1920's, his vivid observations would be recorded in both fiction and non-fiction in an attempt to raise public awareness and appeal for reform. He is best known for his novels, Tobacco Road (1932) and God's Little Acre (1933). An adaptation of Tobacco Road played on Broadway for eight years - a record at the time - beginning in 1933. God's Little Acre remains one of the most popular novels in the U.S. with over ten million copies in print. A 1958 film version is considered the best presentation of Caldwell themes on film.
A very loose 1941 film adaptation of Tobacco Road directed by John Ford contributed to the stereotyping and ridicule of poor white Southerners. Furthermore, his "in absentia" crusade for improving conditions did not sit well with many Southerners. They were also uncomfortable with his depiction of sex and violence that frequently placed him in conflict with censors across the country.
Read more about Georgia's Erskine Caldwell in this article from the New Georgia Encyclopedia. The volume is also the information source for this post.