US Slavery in the 1940's?

According to this article, STLtoday - Slavery by Another Name, slavery existed in the US until the 1940's through "legal" means. "In March 1908, an unemployed black man named Green Cottenham was arrested in Alabama and found guilty of the vague charge of vagrancy. Unable to pay exorbitant fines and fees that accompanied the conviction, he was sentenced to a year at hard labor and "sold" to a mining subsidiary of U.S. Steel, which agreed to pay his debts in return for his services and sent him in chains into a coal mine." This kind of servitude continued into the 1940's. Still slavery. Numerous African-Americans were arrested on trumped up charges and "sold" into servitude for their debts to be paid.