We show that isolated capital cities are robustly associated with greater levels of corruption across US states. In particular, this is the case when we use the variation induced by the exogenous location of a state’s centroid to instrument for the concentration of population around the capital city. We then show that different mechanisms for holding state politicians accountable are also affected by the spatial distribution of population: newspapers provide greater coverage of state politics when their audiences are more concentrated around the capital, and voter turnout in state elections is greater in places that are closer to the capital. Consistent with lower accountability, there is also evidence that there is more money in state-level political campaigns in those states with isolated capitals. We find that the role of media accountability helps explain the connection between isolated capitals and corruption. In addition, we provide some evidence that this pattern is also associated with lower levels of public good spending and outcomes.