The economic trajectory and development of capitalism in the United States are inextricably linked to the brutal institution of slavery. A new working paper shows how central this system of violence and forced labor was to the country’s economic growth in the years leading up to the Civil War, which continues to shape racial inequities for Black Americans today.

The new working paper by economist Mark Stelzner of Connecticut College and historian Sven Beckert of Harvard University, titled “The Contribution of Enslaved Workers to Output and Growth in the Antebellum United States,” provides the first in-depth estimates of enslaved workers’ contributions to regional and national economic growth between 1839 and 1859.

Stelzner and Beckert show that the work of enslaved Americans was an important driver of growth not only in the South but also for the national economy as a whole, comparable to the growth in per capita output of manufacturing workers in New England. Their findings also show that income inequality increased between White Southern households with enslaved Americans and those without—a socially and politically destabilizing factor in the antebellum South.

The authors write that their findings demonstrate that “slavery was an important institution for economic development in the United States, and that the unrequited labor of enslaved women, men and children helped produce in significant ways the nation’s economic expansion in the two decades before the Civil War.” This research is important to understand the role of slavery in U.S. economic history and, by further quantifying the exploitation of enslaved people, can contribute to discussions of reparations and the legacy of slavery today.