All-day kindergarten at no charge to families finally arrived in Minnesota this week, 30 years after then-Gov. Rudy Perpich began discussing that change in earnest at the State Capitol. Public policy changes often take years, but this one should have come much sooner to Perpich's "Brainpower State."

The change is a boon for families, some of whom had been paying as much as $4,000 a year for their children to spend a second half-day in kindergarten each day, and some of whom lived in school districts that previously did not offer an all-day kindergarten option at any price.

Enacted by the 2013 Legislature at the urging of Gov. Mark Dayton, the change will cost state taxpayers $134 million this year, a modest sum compared with the $8.5 billion the state will spend on K-12 education in 2014-15. It should produce a big long-term payoff in student success. Studies show that learning accelerates when children are in kindergarten all day rather than half-days, with gains most noted among students who are English language learners and/or from low-income families — those who today are at the lagging end of Minnesota's persistent achievement gap.

Some of those same studies also point to what ought to be Minnesota's next educational policy push — more, better and more affordable preschool. For at-risk children, optimal results come from the reinforcing combination of quality preschool and all-day kindergarten. Offering those children that one-two punch ought to be a high priority for a state whose prosperity much depends on its well-educated workforce.

For too long at the Legislature, all-day kindergarten and preschool competed for scarce dollars, with neither cause sufficiently advancing. That picture changed beginning in 2013 with Minnesota's improving economy and growing support for early learning within both parties at the Legislature.

A preschool push has already begun at the Legislature, with $44.6 million for fiscal 2014-15 pumped into early learning scholarships for low-income families. In this fall's campaign, Minnesotans should hear from candidates for governor and the state House how they intend to build on that foundation, with a goal that every child arrives in kindergarten ready to learn.