The state laws that barred nearly six million people with felony convictions from voting in the midterm elections this month date from the late 19th and early 20th centuries, when Southern lawmakers were working feverishly to neutralize the black electorate.

Poll taxes, literacy tests, grandfather clauses and cross burnings were effective weapons in this campaign. But statutes that allowed correctional systems to arbitrarily and permanently strip large numbers of people of the right to vote were a particularly potent tool in the campaign to undercut African-American political power.

This racially freighted system has normalized disenfranchisement in the United States — at a time when our peers in the democratic world rightly see it as an aberration. It has also stripped one in every 13 black persons of the right to vote — a rate four times that of nonblacks nationally. At the same time, it has allowed disenfranchisement to move beyond that black population — which makes up 38 percent of those denied the vote — into the body politic as a whole. One lesson here is that punishments designed for one pariah group can be easily expanded to include others as well.

The history of disenfranchisement was laid out in a fascinating 2003 study by Angela Behrens, Christopher Uggen and Jeff Manza. They found that state felony bans exploded in number during the late 1860s and 1870s, particularly in the wake of the Fifteenth Amendment, which ostensibly guaranteed black Americans the right to vote.