American slavery took root in the early eighteenth century on the tobacco plantations of the Chesapeake and in the rice fields of the Carolina low country. However, it grew to maturity during the first half of the nineteenth century on the cotton fields and sugar plantations of the Mississippi Valley. By then, a small elite of extraordinarily wealthy planter families stood at the top of southern society. These families — about three thousand in number — each owned more than one hundred slaves and huge tracts of the most fertile lands. Their ranks included many of the richest families in the United States. On the eve of the Civil War, southern slave owners accounted for nearly two-thirds of all American men with wealth of $100,000 or more. Other white southerners — backcountry yeomen farmers and cotton-planting tenants in particular — occupied some of the lowest rungs of the nation’s social order. The expansion of southern slavery, like the flowering of northern capitalism, increased inequalities of wealth and status.