Federalism essentially allows us a controlled experiment in which we can examine which policies work and which don't by examining the contrasts between states that have chosen different paths. The results, as Joel Kotkin notes at the Daily Beast, are pretty lopsided:

The North and South have come to resemble a couple who, although married, dream very different dreams. The South, along with the Plains, is focused on growing its economy, getting rich, and catching up with the North’s cultural and financial hegemons. The Yankee nation, by contrast, is largely concerned with preserving its privileged economic and cultural position—with its elites pulling up the ladder behind themselves.

... While the Northeast and Midwest have become increasingly expensive places for…[more]