As described in the thirteenth amendment, involuntary servitude was

As described in the Thirteenth Amendment, involuntary servitude was abolished.

Explanation:

The 13th Amendment to the Constitution of the United States of America abolished slavery and involuntary servitude in the United States, except in the case of punishment for a crime. It obtained the special two-thirds majority required to amend the constitution and was passed by Congress on December 6, 1865.  

At the time of its ratification, slavery was still legal in Delaware, Kentucky, Missouri, Maryland, and West Virginia, slavery states that remained in the Union after the secession of the Confederate States, the cause of Civil War. Everywhere else in the United States the slaves were freed either by standards adopted previously and individually by the states, or, failing that, by the proclamation of emancipation of Abraham Lincoln, a proclamation that had applied since January 1, 1863.