Fence construction deters migration because the migration costs faced by prospective migrants are sensitive to the particular set of available crossing locations; plus the fence disproportionately deters low-skilled migrants

Fenced Out: Why Rising Migration Costs Matter. Benjamin Feigenberg. American Economic Journal: Applied Economics, Forthcoming. https://www.aeaweb.org/articles?id=10.1257/app.20170231&&from=f

Abstract: This paper estimates the impact of the U.S.-Mexico border fence on U.S.-Mexico migration by exploiting variation in the timing of U.S. government investment in fence construction. Using Mexican household survey data and data I collected on fence construction, I find that construction in a given municipality reduces migration by 29% from that municipality and by 15% from adjacent municipalities. I also find that construction reduces migration from non-border municipalities by 32%. I employ a standard migration selection model to rationalize evidence that the fence disproportionately deters low-skilled migrants. The estimated cost of the fence per migrant deterred is $2,850 USD.

Old abstract: Spending on border enforcement has risen by 240% in the United States in the last decade and the construction of a fence on the U.S.-Mexico border has become a focal point in the debate over the costs and benefits of increased border security. However, whether and by how much the fence actually reduces migration from Mexico to the United States remains an open question. This paper estimates the impact of the fence on migration flows between Mexico and the United States and investigates the mechanisms driving observed impacts. To conduct this analysis, I exploit variation in the timing of U.S. government tactical infrastructure investment in fence construction in the period after the passage of the 2006 Secure Fence Act. Using Mexican household survey data and data I collected on border fence construction, I find that construction in a given municipality reduces migration by 39% from that municipality and by 26% from adjacent municipalities. I also find evidence that fence construction reduces migration rates for residents of non-border states with historically low access to smugglers by 38%. Based on these estimates, I calculate that the implied cost of the fence per migrant deterred is $4,800 USD. My findings suggest that fence construction deters migration because the migration costs faced by prospective migrants are sensitive to the particular set of available crossing locations. I derive a simple migration selection model to test this hypothesis and find that a left-censoring of the migration cost distribution, consistent with the disproportionate elimination of low-cost crossing options, best rationalizes evidence on changing migration patterns.