From Think Progress:
...Approximately 57,000 Virginians have been flagged as being registered in another state, and counties are removing some from the voter rolls without any notice or opportunity to rebut the claim. Before conservatives lose their marbles that this is clear and irrefutable evidence of voter fraud, it’s worthwhile to consider how voter registration works. Each state maintains its own roll rather than a nationwide system. When Joe America, who had been registered in Richmond, moves to Philadelphia and registers there, he’s not required to cancel his Virginia registration before enrolling in Pennsylvania. The process for removing registrations of people who have moved elsewhere varies from state to state, but generally involves periodic comparisons of lists between states to flag and remove people like Joe America who have moved elsewhere.
First and foremost, as multiple county registrars explained to ThinkProgress, voters whose registrations are being cancelled aren’t being given any advance notice. Rather than being mailed a warning letter asking if they still live in Virginia, they are being sent notices that their registration has been cancelled effective immediately. If the cancellation is in error, the letter says to contact the registrar and get it worked out. It’s not measure twice, cut once. It’s cut first and be ready with tape for the mistakes...