(CNN) In 1865, the federal government abolished almost all forms of slavery, but the 13th Amendment allowed for one exception: When the opportunity of servitude was punishment for a crime.

Sixteen state constitutions have similar language, but on Tuesday voters in Colorado elected to change the language of their state's constitution and abolish all forms of slavery.

Article II, Section 26 of Colorado's constitution reads that there "shall never be in this state either slavery or involuntary servitude, except as a punishment for crime, whereof the party shall have been duly convicted." (Emphasis added)

In the future, because of Amendment A, it will read "There shall never be in this state either slavery or involuntary servitude." (Again, emphasis added.)

Not all the votes have been counted, but the amendment had 65% of the vote with more than four-fifths of precincts reporting as of Wednesday, according to the Colorado Secretary of State's Office.

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