Democrats opposed to school choice often claim that charter schools and vouchers siphon taxpayer money from traditional public schools. That’s rarely true because choice schools typically spend less per child. And now a study shows that Milwaukee’s landmark voucher program will save taxpayers hundreds of millions of dollars.

Readers may recall the story of St. Marcus Lutheran, one of Milwaukee’s top schools, which graduates about 90% of its students, more than 90% of whom come from low-income families. St. Marcus participates in the Milwaukee Parental Choice Program and is in high demand. So when an empty public-school building came on the market in 2014 for an appraised value of $880,000, St. Marcus saw it as a chance to add a second campus for as many as 600 more students.