Most polling places are staffed by locals and will often recognize someone trying to commit fraud. If the person who you are trying to impersonate also votes,

Most polling places are staffed by locals and will often recognize someone trying to commit fraud. If the person who you are trying to impersonate also votes, it will also trigger an event. Worst case you show up to vote after someone has already voted, you trigger this event and get busted. Theoretically the only people you could safely impersonate would be dead and un-likely to be known to the pollster. Even if you found that, how many times could you vote? You'd risk someone recognizing you the second time, so you'd have to try and visit multiple polling places. The most likely place for fraud to occur would be after the vote takes place: either in the counting system, or tampering with the votes. There is not much chance of changing enough votes simple by showing up and casting a physical ballot, unless you have a high enough number of people doing it (and somehow not getting caught and triggering an investigation).