As with so many generalizations about the U.S., it's more complicated than that, and varies on a state-by-state basis.
Most people in jail retain the right to vote, regardless of state.
People currently in prison on felony charges CANNOT vote in most states, but this is up to each state. In many states, you get your enfranchisement restored after completing your sentence.
I used to think the same thing, until I read an article that made me look into it. The article I read was a local affair that pointed out that inmates are encouraged (in my state, Maine) to file absentee ballots in the town they lived in prior to incarceration.
There are just a couple of states that allow that, but I learned that quite a few jurisdictions restore rights after incarceration, after probation, etc...
Most people in jail retain the right to vote, regardless of state.
People currently in prison on felony charges CANNOT vote in most states, but this is up to each state. In many states, you get your enfranchisement restored after completing your sentence.
https://www.thoughtco.com/where-felons-can-and-cannot-vote-3...