You see, some states have instituted voter ID laws, or made the ones they already had on the books even more restrictive.
Those laws keep trans people from voting because many of us live in a legal limbo in which we can get one kind of ID but not another in our names, and the jurisdictions in which we live will only accept the kind of ID we can't get.
As an example, some states won't allow us to change the names on our drivers' licenses until/unless we've had gender reassignment surgery--even if we've changed our names in the local court. Or we've changed our state IDs but the local boards of elections still list us under our old names.
I was in a really peculiar situation: After changing my name, I was able to get a new state (non-drivers' license) ID with my chosen name and a female gender marker. I also got a passport as a woman named Justine, but was not allowed to renew it as such until I underwent my surgery.
Anyway, I will leave you with this "Voting While Trans" guide: