star twitter facebook envelope linkedin instagram youtube alert-red alert home left-quote chevron hamburger minus plus search triangle x

Boll Weevil Reduced Black-White Inequality By Improving Early Life Conditions for Blacks

Inequality between Blacks and Whites has persisted for decades, and researchers have sought to determine the reasons behind it. A new study examined the effect of the boll weevil, a beetle that feeds on cotton buds and flowers, on the lives of Black and White fathers and sons that were impacted by the beetle. The study found that this agricultural shock in the first half of the 20th century induced large-scale migration, affecting Black and White fathers and sons differently, with unexpected improvements for Black sons regardless of whether their fathers migrated. The findings deepen our understanding of racial inequality.

The study, by researchers at Carnegie Mellon University (CMU), Washington and Jefferson College, and the University of Pittsburgh, will be published as a working paper of the National Bureau of Economic Research.

“Although our research addresses something that happened years ago, the findings shed light on issues of contemporary interest,” says Karen Clay, professor of economics and public policy at CMU’s Heinz College, who led the study. “By focusing on the intergenerational effects of shocks that induce migration, particularly for disadvantaged groups, our study highlights the importance of the early life environment and schooling access for the children of families that migrate and those that do not.”

The boll weevil spread throughout the American South between 1892 and 1922, decreasing cotton production, disrupting tenancy arrangements, and leading to widespread migration—ultimately, about a fifth of the U.S. population was affected by the beetle.

Researchers used Census data from 1900 and 1910 to identify fathers who had sons ages 18 or younger and who lived in a county that would be invaded by the beetle in the next 10 years. They then linked these fathers to the next Census (1910 or 1920) to determine whether the fathers migrated out of their initial county, state, or region of residence. Next, they linked the sons of these fathers (those who had been identified in the 1900, 1910, or 1920 Censuses) to the 1940 Census to determine the sons’ years of schooling, occupation, income, and patterns of migration. The authors collected information on 42,000 Black fathers, 55,000 Black sons, 136,000 White fathers, and 195,000 White sons.

Based on these data, the researchers found that the boll weevil induced enormous labor market and social disruption as more than half of Black and White fathers moved to other counties following the arrival of the beetle. The study compared Black and White sons whose fathers initially lived in the same county to find that the agricultural shock affected them differently.

White sons born after the boll weevil’s arrival had similar wages and schooling outcomes as White sons born before its arrival. In contrast, Black sons born after the beetle’s arrival had significantly higher wages and more years of schooling than Black sons born before the beetle’s arrival, regardless of whether their fathers migrated. These changes narrowed the Black-White wage gap 12% to 22% and the Black-White schooling gap 6%.

The study’s authors suggest that this narrowing was driven by relative improvements in early life conditions and access to schooling for the Black sons, and that these improvements affected both sons of Black fathers who migrated out of the South after the beetle’s arrival and sons of Black fathers who stayed in the South. In the early 20th century, Blacks were extremely impoverished; the arrival of the beetle likely improved maternal, fetal, and infant health by reducing mothers’ working conditions, say the authors. In addition, the variety and nutritive value of food production improved after the boll weevil, which could have led to improvements in the health of Black infants.

“Most research on the Black-White wage gap has focused on migration as a source of change,” explains Ethan Schmick, assistant professor of economics at Washington and Jefferson College, who coauthored the study. “We found that the boll weevil improved early life conditions of Black sons born after its arrival. Thus, agricultural disasters can lead to relative improvements for impoverished populations in the next generation.”

The research was funded by Heinz College, Carnegie Mellon University.


Summarized from an NBER working paper, Changes in Black-White Inequality: Evidence from the Boll Weevil by Clay, K (Carnegie Mellon University), Schmick, E (Washington and Jefferson College), and Troesken, W (University of Pittsburgh). Copyright 2020. All rights reserved.

About Heinz College of Information Systems and Public Policy
The Heinz College of Information Systems and Public Policy is home to two internationally recognized graduate-level institutions at Carnegie Mellon University: the School of Information Systems and Management and the School of Public Policy and Management. This unique colocation combined with its expertise in analytics set Heinz College apart in the areas of cybersecurity, health care, the future of work, smart cities, and arts & entertainment. In 2016, INFORMS named Heinz College the #1 academic program for Analytics Education. For more information, please visit