“…The exogeneity of the disembarked slaves variable as an instrument for the share of slaves in 1860 is even more realistic if we consider the discontinuity in the economic history of Southern US states provided by the Civil War which is largely documented, for instance, by Fogel and Engerman (1974), Margo (1990), Margo and Hutchinson (2001), and Ransom and Sutch (1977). After the Civil War, slavery is abolished, the gang system is abandoned (Fogel and Engerman, 1974;Ransom and Sutch, 1977), wages fall relative to the North (Margo, 2004), the cost of capital increases, and labor productivity decreases (Margo and Hutchinson, 2001). Therefore those factors which pushed Southern US states to engage in the slave trade, i.e., the relatively high productivity of slaves associated with the gang system, were reverted after the Civil War.…”