Wright argues "that slavery retarded the mechanization of agriculture, the development of manufacturing, the emergence of cities, and immigration to the South; that the South was on the verge of economic crisis in 1860; that tenancy and the associated credit systems caused 'overproduction' of cotton after the war; and that the Civil War was fundamentally caused by the economics of slavery." (p. 4) He comes to these conclusions by looking at the homogenizing effect which slave ownership (and the potential for slave ownership) had on farmers -- big and small -- in the South. Because slave labor allowed for the allocation of labor to market production, the South became linked to the international cotton market early on and thereby to the vicissitudes of world cotton demand. Lacking slaves in the North, a creative tension which led to mechanization of agriculture and industrialization. The equity value in slave property drove the Southern conception of wealth. This tied them to the cotton crop and left them vulnerable to the market.
Wright develops this focus on the nature of property ownership in the North and South in a section called "On Making Economic Sense of Cotton, Slavery, and the Civil War." He he argues as follows:
In the North, property rights in labor were prohibited, and, hence, efforts to augment property values focused on land: land clearing and improvement, promotion of canals and railroads to improve access to markets, attracting immigrants through vigorous recruitment and offers of credit, schools, roads, etc. In the South one could own slaves, and for this reason much of the same drive toward property accumulation was channeled along very different lines. In the North energies went toward raising the values of local farms and local areas because land is not moveable; in the South there was relatively little a slave owner could do to raise the value of individual slaves, though he could hope to accumulate slave property over time by fostering high fertility and low mortality. Slaves were moveable personal property; the value of an owner's slave property was determined not by his individual behavior, but by regional slave markets and world cotton markets, and this value was essentially uniform in all parts of the slave South at any moment. (p. 129)
There are several "economic" interpretations, which Wright debunks - the war was not a conflict between agrarian interests and industry, nor was it caused by competition of land in the west (at least not directly) as the South had plenty of land to grow cotton on in the South. It was expansion of slavery into the territories that aroused Southern ire, not expansion per se. Since Northern politicians had the politically expedient free labor rhetoric to fall back on, they could please the abolitionists by arguing that slavery would actually die out if contained -- without having to press for abolition per se. Free labor also had the appeal of brining western interests under the "big tent." There was no political benefit to the North in respecting the "peculiar institution."
It was, above all, the capital gains in slave values that united small and large planters with all those who hoped some day to be planters in the South:
the capital arising from rising slave prices were sufficient to make financial successes of all but the most incompetent slaveowners. The fact is that virtually every slaveholder who was careful enough to keep his slaves alive made at least a nominal profit during the 1850s from capital gains alone. (p. 141)
The value which Southerners held in slave property was a great unifying force in the 1850s. Similar to home ownership in the 1990s, it was tied to long-term calculation of family worth and -- even for those who only had a slave or two -- represented the hope for the future that slaveholders had for their families. Opposition to secession would come mostly from states where slave holding was limited. Southerners were touchy on this subject, seeing any implicit threat to the value of slaves as a threat to their prosperity and their posterity. Deeply immersed in market capitalism, the very perception of slave values was of far reaching consequence. Even reopening the slave trade, which was bandied about in the South in the 1850s didn't get much support because it might lower slave property values. Blinded by the power of King Cotton, secessionists believed that the Union would be too concerned about provoking England's wrath to stop secession.