Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
American and foreign businesses, politicians, and media have all pointed to post-9/11 changes in visa policies as being responsible for the sharp decline in travel to the United States following the attacks. Using an empirical model which distinguishes the impact of visa policy from economic and country-specific factors, we find that changes in visa policy were not important contributors to the decrease in travel to the United States. Rather, the reduction in entries was largest among travelers who were not required to obtain a visa.