“More than 150 years after the ratification of the US Constitution’s 13th Amendment, Colorado has officially abolished slavery. Coloradans voted Tuesday for Amendment A, a measure removing language in the state constitution that allowed prison labor without pay. Colorado is one of more than a dozen states whose state constitution technically still allows involuntary servitude as a form of criminal punishment. The state’s language closely resembles a contested passage that remains in the US Constitution 13th Amendment, which outlawed chattel slavery, but allowed those convicted of crimes to be forced into labor.”