The print edition of The New York Times of February 12 has this editorial, calling on all states to enable ex-felons to register to vote.
There are three fairly large groups of legally competent adult citizens who are not permitted to vote freely in parts of the United States: (1) ex-felons; (2) residents of territories (and, to a lesser extent, residents of the District of Columbia); (3) supporters of minor party and independent candidates.