Walker Hanlon is an Assistant Professor at UCLA, a Faculty Research Fellow at the NBER, and a Research Associate at the California Center for Population Research. He received his Ph.D. from Columbia University in 2012. Prof. Hanlon’s research focuses on understanding the forces driving innovation and economic growth over the long term using novel historical data sources. In one strand of ongoing research, he considers how changes in the availability of inputs to production influences the rate and direction of technological progress, with particular emphasis on directed technical change theories. An example of his work in this area, “Necessity is the Mother of Invention: Input Supplies and Directed Technical Change,” uses the impact of the U.S. Civil War on the British cotton textile industry to evaluate the leading theory of directed technical change. This paper has received a second R&R request from Econometrica. In a second strand of research, he considers how spillovers between industries affect industry and city growth over the long-term. An example of his work in this area, “Industry Connections and the Geographic Location of Economic Activity,” shows that the temporary localized shock to the British cotton textile industry generated by the U.S. Civil War caused long-term shifts in the geographic location of industries across British cities. This provides the first causal evidence that a temporary localized shock, working through inter-industry connections, can have a long-term impact on the location of economic activity. Prof. Hanlon’s research has been funded by numerous research grants, including an NSF Dissertation Improvement Grant, a PEDL Exploratory Grant from the Center of Economic Policy Research, an Economic History Association Exploratory Data and Travel Grant, and numerous internal grants at UCLA and Columbia University. He has presented his work at invited seminars and conferences in both the U.S. and abroad, including the NBER Summer Institutes, the Urban Economics Association Annual Conference and the Economic History Association Annual Conference. He teaches a popular undergraduate course in Urban Economics and a graduate course in European Economic History.