In only two states, Maine and Vermont, all prisoners are eligible to vote. However, some prisoners in Mississippi, Alaska and Alabama can vote while incarcerated, depending on their convictions. Sanders is the sole presidential candidate to support the idea of prisoners voting, regardless of their crimes. His stance may reflect the reality that his home state of Vermont, and its neighbor Maine, have long-established procedures, and general public acceptance, of people voting from behind bars.

Why are Vermont and Maine outliers? They share several characteristics that make voting by prisoners less controversial. Incarcerated people can only vote by absentee ballot in the place where they last lived. They are not counted as residents of the town that houses a prison, which means their votes can’t sway local elections if they vote as a bloc. And unlike many states, the majority of prisoners in Maine and Vermont are white, which defuses the racial dimensions of felony disenfranchisement laws.

Corrections officials in both states encourage inmates to vote, but rely on volunteers to register inmates. In recent election years, voting advocacy organizations such as the League of Women Voters and the NAACP have coordinated with corrections departments to hold voter registration drives in the prisons. To bridge the information gap, they share one-pagers with information about the state candidates and explain their positions on key issues.

Yet the barriers to voting, both external and internal, remain high. Incarcerated people are restricted from using the Internet and often cut off from news in the places they used to live. They are not allowed to campaign for candidates, display posters or show other signs of political partisanship.

Experts and volunteers who try to encourage voting from prison suspect that very few actually exercise the rights they have. Neither corrections department tracks inmate voting or registration, so statistics on participation or the political ideologies of prisoners are unavailable. Because their votes are counted along with other absentee ballots, election officials in Maine and Vermont do not specifically tally how many incarcerated people vote.

Read the full article about prisoners with voting rights by Nicole Lewis at The Marshall Project.