Oh, I'm familiar with that. It's just that most don't take away the right to vote permanently. They take it away until you're done serving your sentence and then it is automatically restored. (See the link.)

A couple of States even allow inmates to vote while incarcerated. In my now-home State, inmates are encouraged to vote and sometimes politicians will even go campaign inside the prison. That's pretty rare, but has happened.

So, it's a temporary loss in most cases. Notably, Maine allows inmates to vote and Maine is overwhelmingly white. Vermont is the same way. In my quest for more information, I found some commentary about that aspect.