In every American election there are some voters who show up to their polling place ready to cast a ballot, only to find their name isn't on the registration list. The reason? Voter purges, an often flawed effort to update voter rolls by removing voters' names from registration lists. Virginians fell victim in 2013, when nearly 39,000 voters were removed when the state relied on faulty data to determine which names should be deleted. In 2016 it was New Yorkers, when the New York City board of elections wrongly deleted more than 200,000 names. A new Brennan Center report found that purges could threaten the right to vote for millions in November. Purges have increased particularly in a handful of largely southern states which were freed from oversight by the supreme court's landmark 2013 decision in Shelby County v Holder. Before Shelby County, areas around the country with histories of racial discrimination in voting were prohibited from making election changes without first showing that the change would not make minority voters worse off. Some states and jurisdictions are using bad information to determine who should be removed from the rolls, like relying on a faulty list that flags eligible voters as ineligible. Some are depending on matching criteria used by a problematic purge database called Crosscheck, which has been found to be more likely to flag African American, Asian American and Latino voters for removal than Caucasian voters.