Why Bad Policies Spread (and Good Ones Don't)

Building on a deep theoretical foundation and drawing on numerous examples, we examine how policies spread across the American states. We argue that for good policies to spread while bad policies are pushed aside, states must learn from one another. The three ingredients for this positive outcome are observable experiments, time to learn, and favorable incentives and expertise among policymakers. Although these ingredients are sometimes plentiful, we also note causes for concern, such as wh...