One characteristic of this age of political polarization is increasing conflict between states and their cities. Pandemic-related regulation has been a recent flashpoint, with governors and mayors at loggerheads over public health regulations. But conflicts between state and city officials preceded that global emergency. Though popular electoral maps can sometimes suggest that red state and blue state divisions are driving our current politics, state-city conflicts are more representative of the actual political cleavages that afflict “our federalism” in the twenty-first century—a federalism that is characterized by the decline of regional political affiliations and the rise of metropolitan ones, the broader conflict between urbanizing municipalities and rural counties, the fact of uneven economic development, and the consequent values bifurcation between low and high productivity places. This form of sectional conflict is less amenable to federalism doctrines that contemplate state-by-state divergence; those doctrines can only serve as crude proxies for the political cleavages that are operating within states, not between them. Recognizing the metropolitan origins of our polarized politics is important for two reasons. First, reorienting the conversation away from state-national conflict highlights the disadvantages of state-based federalism as a mechanism for managing ideological cleavages. And second, focusing on state-city conflict suggests the necessity of intra-state institutional reform as a way forward. State-city conflict is not federalism writ small; it is instead what federalism—albeit mediated through a pre-urban Constitution that still gives primacy to states—has become. Instead of “federalism all the way down” as a way to characterize the multiple vertical layers of authority in the U.S., a better description might be “localism all the way up”: conflict at the metropolitan scale is driving important aspects of our national political life.