Juan Landeros-Mireles admitted in court last year that he registered to vote and even cast ballots in the 2016 election, though he has never been a U.S. citizen. As the November election nears, he is still listed as an active voter in Wilson County, North Carolina. Given his past, it’s not likely he will try again, but his experience does strengthen an argument of voter integrity advocates: Some local rolls haven’t been cleansed of illegitimate voters, creating opportunities for fraudulent ballots to be cast. Landeros-Mireles isn’t alone. Federal prosecutors charged 17 other people with illegally voting as noncitizens in eastern...