Sun Kyoung Lee Receives IPUMS Research Award

Yale Economics and Economic Growth Center postdoctoral associate, Sun Kyoung Lee, is a recipient of one of this year’s IPUMS Research Awards. The awards honor the best published research and self-nominated graduate student papers from 2019 that used IPUMS data to advance or deepen our understanding of social and demographic processes.

Lee’s paper titled, “Crabgrass Frontier Revisited in New York: Through the Lens of 21st-century Data“ aims to understand the suburbanization process of New York City between 1870 and 1940.  The common understanding set forth by Kenneth T. Jackson’s book, Crabgrass Frontier: The Suburbanization of the United State (1985), is that wealthy households, who where richer than those before them, moved to the periphery of the city, while the poorest stayed in the core. Lee’s study shows that this suburbanization process was not entirely true in New York City. People who stayed in the core were wealthier than the ones who left the city center and those who moved to the periphery where poorer than those already living there. Moreover, the people who stayed at the periphery got richer as the metropolis grew.

According to Lee, it was after reading Ed Glaeser’s paper “Urban Colossus: Why Is New York America’s Largest City?” that she began to develop a process for her research. “My interests in these issues grew organically over time,” said Lee. 

Also fascinated by Jacob Riis’s photojournalism book “How the Other Half Lives” profiling poor, immigrant families living in late 19th century New York City, Lee yearned to understand, “what happened to the other half when the city was growing at a spectacular rate.” She questioned whether there were channels of moving out of poverty and living in better environments; if and where they could move from city slums, and whether economic inequality within the city grew while going through explosive economic growth.

“Earlier forms of American suburbanization painted quite different pictures relative to postwar suburbanization; it looked more like Paris where the rich lived in the city core, and the poor lived in the city periphery,” said Lee. “Moreover, new suburbanites to the city periphery were not richer than the people who already lived there (which debunks the “displacement” hypothesis). Furthermore, people who stayed at the periphery got richer as the metropolis grew.”

Lee’s findings show the pre-war suburbanization process and the mechanism behind the city periphery’s growth has implications beyond local history. ”I think there exists this notion that American cities became suburbanized after post-WWII due to the construction of highways, and the affluent and educated households moved from the city core to the periphery, and the poor stayed in the city center,” said Lee. “However, my research through longitudinal data analysis shows that suburbanization in American cities began before the postwar period.”

To better understand the relationship between the social groups, Lee’s research, funded by a National Science Foundation grant, has been developing various record-linking techniques to associate different types of records across sources, times, and languages. She hopes these techniques will unlock research that was impossible to conduct before datasets were available.

Lee has extended the scope of her analysis to other major American cities to document the pattern of suburbanization and analyze the welfare consequences of city growth. To assist in following individuals over time, she has constructed a massive database for multiple generations of grandfathers, fathers, and sons to study intergenerational mobility in the United States before World War II (joint with Rodrigo Adao at Chicago Booth, and Costas Arkolakis at Yale).  She hopes that the big-data approach will allow the identifications of locations and times in American history where kids had chances to move up in the income ladder, and plans to share her techniques with other researchers in the field.

Grateful for the mentorship she received from her advisors, Lee was extremely fortunate to work with Don Davis and Dan O’Flaherty.  She likened the relationship of her advisors to parents who had very complementary perspectives by saying, “They were extremely patient and encouraging knowing the nature of my work would require a long time and many resources.”

Lee is in the first of a two-year postdoctoral program at Yale. She received her Ph.D. in Economics from Columbia University in 2019. Her current research focuses on economic history and spatial economics with big data, and she has worked extensively on implementing the machine-learning based approach to connect large datasets.

IPUMS, developed by and housed at the University of Minnesota, is the world’s largest individual-level population database, providing harmonized data on people in the United States and around the world to researchers at no cost.

The full list of recipients can be found on IPMUS’s website.