The line separating what used to be the Union and the Confederacy in America reduces trade between states of the former North and South by 13% to 14%, an effect that is strongest in food, manufacturing, and chemicals, say Gabriel Felbermayr and Jasmin Gröschl of the University of Munich in Germany. Possible reasons: The South’s secession 150 years ago may have had long-term effects on business-to-business trust and consumer preferences for goods, the researchers say. By comparison, the former border between East and West Germany restricts trade by about 26% to 30%.

Source: Within U.S. Trade and the Long Shadow of the American Secession