An influential literature has used the aftermath of terrorist attacks to estimate large effects of police street deployment on crime. However, the elasticities obtained in these settings may not easily extrapolate to more standard circumstances. This paper exploits a natural experiment that...

We test how a reduction in travel cost affects the rate and direction of scientific research. Using a fine-grained, scientist-level dataset within chemistry (1991-2012), we find that after Southwest Airlines enters a new route, scientific collaboration increases by 50%, an effect that is...