If you voted last week, you may have seen some new faces in the line to cast ballots. College kids who have turned 18 since the last election. Naturalized immigrants eager to exercise one of the privileges of citizenship. Even a few ex-convicts.

Or maybe more than a few. In most places, anyone convicted of a felony loses the right to vote for some period — while he’s behind bars, until he’s completed his term of probation, or even for life. But in recent years, 23 states have revised their laws to let more onetime criminals take part in this ritual of democracy, and the changes have had a noticeable effect.