You can tell a lot about prosperity in America by observing the places people are moving to and where they are packing up and moving from. New Census Bureau data on metropolitan areas indicate that the South and the Sunbelt regions continue to grow, while the Northeast and Midwest continue to shrink.

Among the 10 fastest-growing metro areas last year were Raleigh, Austin, Las Vegas, Orlando, Charlotte, Phoenix, Houston, San Antonio and Dallas. All of these are in low-tax, business-friendly red states. Blue-state areas such...