"Even in this precarious moment for American democracy, the institutions of American federalism-that is, state governments-remain almost universally lauded. For many, the present era of national partisan polarization makes local politics even more appealing. The truth about federalism in this polarized age, however, is a bit more concerning, as Grumbach details. As the state level has become an increasingly important site of public policies that affect Americans' lives, it is also accelerating the distressing trends of the current era, including plutocratic politics, racial inequality, and democratic backsliding. The book develops a theory of the interaction between federalism and polarization, debunking common myths and misunderstandings that underpin widespread support of state governments. Whereas the framers thought federalism would incentivize state governments to customize policy to local preferences, the state level is increasingly dominated by national groups who exploit the low-information environments of amateur legislatures, inattentive local media, and identity-focused voters. Not only are well-resourced groups advantaged, but polarization diminishes the incentives for state governments to learn from the experiences of other policy laboratories. A state may risk their party's national reputation by emulating a successful policy from a state controlled by the opposing party. Taken together, this theory of polarized federalism suggests that polarization disrupts the oft-lauded features of federalism so common to theories of American governance"--