Image: Library of Congress

Happy 300th birthday to the city of Natchez, Mississippi! To celebrate, Mississippi Development Authority executive director Glenn McCullough Jr. noted on Twitter that Natchez had the most millionaires per capita of an U.S. city before the Civil War. That’s a lot of millionaires—where do you think they got all their money?

They got it from slavery, as the historian and sportswriter Curtis Harris helpfully pointed out to McCullough after the fact. According to U.S. Census data from 1860, Adams County, where Natchez is located, had a population that was 71.7 percent enslaved that year.

Before the Civil War, any prosperity in Mississippi—and all of the U.S., really—was had thanks to the violent subjugation of black people. If Natchez had a lot of millionaires, it’s because they didn’t have to pay for labor.

McCullough has since deleted the millionaires tweet and replaced it with a much friendlier sentiment.