What is Peonage?

- From Britannica: 

Peonage, form of involuntary servitude, the origins of which have been traced as far back as the Spanish conquest of Mexico, when the conquerors were able to force the poor, especially the Indians, to work for Spanish planters and mine operators. In both the English and Spanish languages, the word peon became synonymous with labourer but was restricted in the United States to those workers compelled by contract to pay their creditors in labour. Although the Thirteenth Amendment to the Constitution and congressional legislation after the American Civil War prohibited any such involuntary servitude in the United States, the former slaveholding states of the South devised certain legislation to make labour compulsory. Under those state laws, employers could induce or deceive men into signing contracts for labour to pay their debts or to avoid fines that might be imposed by the courts.

-From LII: 

Notwithstanding its early acknowledgment in the Slaughter-House Cases that peonage was comprehended within the slavery and involuntary servitude proscribed by the Thirteenth Amendment,24 the Court has had frequent occasion to determine whether state legislation or the conduct of individuals has contributed to re-establishment of that prohibited status. Defined as a condition of enforced servitude by which the servitor is compelled to labor against his will in liquidation of some debt or obligation, either real or pretended, peonage was found to have been unconstitutionally sanctioned by an Alabama statute, directed at defaulting sharecroppers, which imposed a criminal liability and subjected to imprisonment farm workers or tenants who abandoned their employment, breached their contracts, and exercised their legal right to enter into employment of a similar nature with another person. The clear purpose of such a statute was declared to be the coercion of payment, by means of criminal proceedings, of a purely civil liability arising from breach of contract.

- From TSHA: Raymondville Peonage Cases.

The Raymondville peonage cases, which were the first of their kind in Texas history, were tried in the Nueces County federal court in January 1927. Residents of Willacy County were arraigned for violation of federal statutes prohibiting peonage. Among the defendants were Sheriff Raymond Teller, Carl Brandt, Frank Brandt, Justice of the Peace Floyd Dodd, L. K. Stockwell, C. S. Stockwell, Roger F. Robinson, Deputy Sheriff William Hargrove, C. A. Johnson, and R. D. Riesdorph. Although the practice was illegal, peonage labor was used during the early twentieth century in some counties of South Texas, where it had become common to force laborers, usually Mexican or African Americans but also Whites, to work off debts owed to farmers. During times of labor shortage the practice included charging individuals with vagrancy in order to force them into labor; "friendly farmers" paid off their fines and then had the prisoners work off the debt by picking cotton, often under armed guard. The government investigation found more than 400 such vagrancy cases filed in the Raymondville court.