Matt "Metafilter" Haughey got a postcard from his home state of Oregon informing him that he'd been purged from his voter roll because his signature has drifted too much since he first signed up to vote, 15 years ago. He has to go through a bureaucratic process to re-register to vote.
Voter purging attacks aren't hard to counter. Registering to vote if you already have ID and so on is pretty straightforward (creating ID requirements is another matter, since people who have historically been able to vote without ID now have to get ID, and red states often sabotage that process, for example, by closing all the offices that dispense valid ID that are within easy traveling range of poor and/or black neighborhoods).
The reason voter purging works is that its victims only discover that they've been purged when they go to the polls, when it's difficult or even impossible to fix the problem.
But if you just check in a couple weeks in advance (or better yet, bookmark your state's webpage for confirming your registration and set a calendar reminder to check it every two weeks between now and election day), you can easily re-register yourself and nullify the attack.
Democracy dies in the darkness [Matt Haughey/A Whole Lot of Nothing]