“Convict leasing was a system of penal labor practiced in the Southern United States, beginning with the emancipation of slaves at the end of the American Civil War in 1865, peaking around 1880, and officially ending in the last state, Alabama, in 1928. It persisted in various forms until World War II.
Convict leasing provided prisoner labor to private parties, such as plantation owners and corporations such as the Tennessee Coal and Iron Company. The lessee was responsible for feeding, clothing, and housing the prisoners. While northern states sometimes contracted for prison labor, the historian Alex Lichtenstein notes that,
“only in the South did the state entirely give up its control to the contractor; and only in the South did the physical “penitentiary” become virtually synonymous with the various private enterprises in which convicts labored.”
Corruption, lack of accountability, and racial violence resulted in “one of the harshest and most exploitative labor systems known in American history.”  African Americans, due to “vigorous and selective enforcement of laws and discriminatory sentencing”, made up the vast majority—but not all—of the convicts leased.
The writer Douglas A. Blackmon described the system:
“It was a form of bondage distinctly different from that of the antebellum South in that for most men, and the relatively few women drawn in, this slavery did not last a lifetime and did not automatically extend from one generation to the next. But it was nonetheless slavery – a system in which armies of free men, guilty of no crimes and entitled by law to freedom, were compelled to labor without compensation, were repeatedly bought and sold, and were forced to do the bidding of white masters through the regular application of extraordinary physical coercion.” http://en.wikipedia.org/wiki/Convict_lease