" Similarly, the nation’s top wealth holders in 1860 had tended to be its major slaveholders. In total, the United States in 1860 had about four million slaves, and on the open market they were worth at least three billion dollars. That was roughly three times the amount of capital invested in manufacturing, three times the amount invested in railroads, seven times the amount invested in banks, and forty-eight times the amount the federal government spent that year. Only the nation’s real estate was more valuable. "

― , Who Freed the Slaves?: The Fight over the Thirteenth Amendment