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About the Author(s)


Allison Shertzer is a faculty research fellow in the NBER's Development of the American Economy Program. An assistant professor of economics at the University of Pittsburgh, she received bachelor's degrees in industrial engineering and mathematics from Arizona State University in 2006 and a PhD in economics from the University of California, Los Angeles in 2011. She is a member of the boards of editors of Explorations in Economic History and Historical Methods.

Shertzer's main areas of research are cities and immigration in early 20th century America. Her work on the origins of residential segregation by race has been supported by the National Science Foundation. She has also studied how the arrival of European immigrants shaped the provision of public goods in prewar urban areas.

Shertzer traces her ancestry to mid-18th century German immigrants who settled in Pennsylvania, of which she is a ninth-generation resident. She lives in Pittsburgh with her husband and two young daughters.


Randall Walsh is a research associate in the NBER's Environment and Energy Economics Program and a professor of economics at the University of Pittsburgh. He received his bachelor's degree in economics from the University of New Hampshire in 1996 and his PhD from Duke University in 2002. He is a member of the editorial council of the Journal of Environmental Economics and Management.

Walsh's research focuses on issues arising at the various intersections of race, the environment, cities and politics. This work has been supported by both the National Institutes of Health and the National Science Foundation.

Walsh traces his southwestern Pennsylvania roots back to Richard "Big Dickey" Dotson, who prowled the region's woods while serving in the U.S. Army as an "Indian Spy" during the Revolutionary War. He lives in Pittsburgh with his wife and two teenage daughters.


1. E. Ananat, "The Wrong Side(s) of the Tracks: Estimating the Causal Effects of Racial Segregation on City Outcomes," NBER Working Paper 13343, August 2007, and the American Economic Journal: Applied Economics, 3(2), (2011), pp. 34–66; D. Card and J. Rothstein, "Racial Segregation and the Black-White Test Score Gap," NBER Working Paper 12078, March 2006, and the Journal of Public Economics, 91(11-12), 2007, pp. 2156–84; R. Chetty, N. Hendren, P. Kline, and E. Saez, "Where is the Land of Opportunity? The Geography of Intergenerational Mobility in the United States," NBER Working Paper 19843, June 2014, and The Quarterly Journal of Economics, 129(4), 2014, pp. 1553–623.   Go to ⤴︎
2. A. Shertzer, R. Walsh, and J. Logan, "Segregation and Neighborhood Change in Northern Cities: New Historical GIS Data from 1900–30," Historical Methods: A Journal of Quantitative and Interdisciplinary History, 49(4), 2016, pp. 187–97. Go to ⤴︎
3. R. Rothstein, The Color of Law: A Forgotten History of How Our Government Segregated America, New York: Liveright, 2017. Go to ⤴︎
4. D. Card, A. Mas, and J. Rothstein, "Tipping and the Dynamics of Segregation," NBER Working Paper 13052, April 2007, and The Quarterly Journal of Economics, 123(1), 2008, pp. 177–218.   Go to ⤴︎
5. A. Shertzer and R. Walsh, "Racial Sorting and the Emergence of Segregation in American Cities," NBER Working Paper 22077, March 2016.   Go to ⤴︎
6. L. Boustan, "Was Postwar Suburbanization 'White Flight'? Evidence from the Black Migration," NBER Working Paper 13543, October 2007, and The Quarterly Journal of Economics, 125(1), 2010, pp. 417–43.   Go to ⤴︎
7. D. Aaronson, D. Hartley, and B. Mazumder, "The Effects of the 1930s HOLC 'Redlining' Maps," Federal Reserve Bank of Chicago Working Paper, 2017(12).   Go to ⤴︎
8. W. Troesken and R. Walsh, "Collective Action, White Flight, and the Origins of Formal Segregation Laws," NBER Working Paper 23691, August 2017.   Go to ⤴︎
9. Shertzer, T. Twinam, and R. Walsh, "Race, Ethnicity, and Discriminatory Zoning," NBER Working Paper 20108, May 2014, and the American Economic Journal: Applied Economics, 8(3), 2016, pp. 217–46.   Go to ⤴︎
10. A. Shertzer, T. Twinam, and R. Walsh, "Zoning and the Economic Geography of Cities," NBER Working Paper 22658, September 2016. Go to ⤴︎


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