A spatial merger estimator with an application to school district consolidation

This paper develops a spatial merger estimator to explain political integration generally and then applies this method to a wave of school district mergers in the state of Iowa during the 1990s. Our estimator is rooted in the economics of matching and thus accounts for three important features of typical merger protocol: two-sided decision making, multiple potential partners, and spatial interdependence. Rather than simply explaining when a particular region is likely to experience a wave of political integration, our method allows us to explore the factors driving which specific subregional mergers take place. This allows us to explore how those districts that merge choose with which of their neighbors to do so. Our results highlight the importance of state financial incentives for consolidation, economies of scale, diseconomies of scale, and a variety of heterogeneity measures in this particular application. We also demonstrate the power of our estimator, relative to existing estimators, to detect a statistically significant role for heterogeneity factors. While our application is limited to school district consolidation, our method can be adapted to include the salient features of many spatial integration problems.