As natural disasters continue to affect the world, two papers by U-M Economists continue to be cited. The first study, “Taken by Storm: Hurricanes, Migrant Networks, and U.S. Immigration,” was authored by Professor Dean Yang and graduate student Parag Mahajan. The second study, “The Effect of Natural Disasters on Economic Activity in US Counties: A Century of Data,” was authored by Leah Platt Boustan (Princeton University), Matthew E. Kahn (University of Southern California), Paul W. Rhode (U-M), and Maria Lucia Yanguas (UCLA).

In the Vox article, "What the Hurricane Maria migration will do to Puerto Rico – and the US,” both studies are cited to reinforce that major disasters increase migration. One focuses on out-migration, leaving the counties affected, while the other looks at the immigration of populations to the US. According to the article, “In the near term, migration will enable Puerto Ricans to escape the extreme economic hardship of a post-disaster island. But in the long run, their choice to either stay on the mainland or return home will have major effects on both.”

Taken by Storm: Hurricanes, Migrant Networks, and U.S. Immigration


How readily do potential migrants respond to increased returns to migration? Even if origin areas become less attractive vis-à-vis migration destinations, fixed costs can prevent increased migration. We examine migration responses to hurricanes, which reduce the attractiveness of origin locations. Restricted-access U.S. Census data allows precise migration measures and analysis of more migrant-origin countries. Hurricanes increase U.S. immigration, with the effect increasing in the size of prior migrant stocks. Large migrant networks reduce fixed costs by facilitating legal immigration from hurricane-affected source countries. Hurricane-induced immigration can be fully accounted for by new legal permanent residents (“green card” holders).

The Effect of Natural Disasters on Economic Activity in US Counties: A Century of Data


Major natural disasters such as Hurricanes Katrina and Sandy cause numerous fatalities, and destroy property and infrastructure. In any year, the U.S experiences dozens of smaller natural disasters as well. We construct a 90 year panel data set that includes the universe of natural disasters in the United States from 1920 to 2010. By exploiting spatial and temporal variation, we study how these shocks affected migration rates, home prices and local poverty rates. The most severe disasters increase out migration rates and lower housing prices, especially in areas at particular risk of disaster activity, but milder disasters have little effect.