State-specific licensing policies and pension plans create mobility costs for educators who cross state lines. We empirically test whether these costs affect production in schools--a hypothesis that follows directly from economic theory on labor frictions--using geo-coded data from the lower-48 states. We find that achievement is lower in mathematics, and to a lesser extent in reading, at schools that are highly-exposed to state boundaries. A detailed investigation of the selection of schools into boundary regions yields no indication of systematic differences between boundary and non-boundary schools along other measured dimensions. Moreover, we show that cross-district labor frictions do not explain state boundary effects. Our findings are consistent with the hypothesis that cross-state mobility costs induce frictions in educator labor markets that lower student achievement. The following are appended: (1) Supplementary Figures and Tables; and (2) Sensitivity Analysis.