How Wisconsin tests its voting machines to ensure election accuracy

Wisconsin is holding congressional and state primary elections this Tuesday. They're seen by some as a dry run for November when the battleground state will play a crucial role in deciding the next president. Election officials have been increasingly transparent about voting mechanics to help boost confidence for the state’s 3.5 million registered voters. William Brangham reports.

Watch PBS News for daily, breaking and live news, plus special coverage. We are home to PBS News Hour, ranked the most credible and objective TV news show.