Call the Ozarks "middle America" if you have to, but don't call it middlebrow. The gob-stopping $1.2 billion Crystal Bridges Museum of American Art opens next Friday in Bentonville, Ark. Funded by the Walton Family Foundation and stocked by Alice Walton, daughter of Wal-Mart's founder, the place is heaving with works by artists from John Singer Sargent to John Baldessari. You can take all those MOMAs, I'm happy here.

Set among the hickory and tulip trees on 120 acres of woodland,...