It’s National Charter Schools Week, when advocates speak out for the 3.2 million students — 6% of all public school students — educated at charter schools, a thriving public education option that is increasingly popular with families.

Since the first public charter school opened one quarter of a century ago, the charter school reform has spread to 47 states and U.S. territories. In historically troubled school districts, student enrollment has grown dramatically. In New Orleans, Detroit and Washington, D.C., the share of students enrolled in public charter schools is 92%, 53%, and 47%, respectively.