The American Slave Coast: A History of the Slave-Breeding Industry by Ned & Constance Sublette is a book which offers an alternate view of slavery in the United States. Instead of treating slavery as a source of unpaid labor, as it is typically understood, they focus on the ownership aspect: people as property, merchandise, collateral, and capital. From a review of the book at Pacific Standard:
In fact, most American slaves were not kidnapped on another continent. Though over 12.7 million Africans were forced onto ships to the Western hemisphere, estimates only have 400,000-500,000 landing in present-day America. How then to account for the four million black slaves who were tilling fields in 1860? "The South," the Sublettes write, "did not only produce tobacco, rice, sugar, and cotton as commodities for sale; it produced people." Slavers called slave-breeding "natural increase," but there was nothing natural about producing slaves; it took scientific management. Thomas Jefferson bragged to George Washington that the birth of black children was increasing Virginia's capital stock by four percent annually.
Here is how the American slave-breeding industry worked, according to the Sublettes: Some states (most importantly Virginia) produced slaves as their main domestic crop. The price of slaves was anchored by industry in other states that consumed slaves in the production of rice and sugar, and constant territorial expansion. As long as the slave power continued to grow, breeders could literally bank on future demand and increasing prices. That made slaves not just a commodity, but the closest thing to money that white breeders had. It's hard to quantify just how valuable people were as commodities, but the Sublettes try to convey it: By a conservative estimate, in 1860 the total value of American slaves was $4 billion, far more than the gold and silver then circulating nationally ($228.3 million, "most of it in the North," the authors add), total currency ($435.4 million), and even the value of the South's total farmland ($1.92 billion). Slaves were, to slavers, worth more than everything else they could imagine combined.
Just reading that turns my stomach. The Sublettes also recast the 1808 abolition of the transatlantic slave trade as trade protectionism.
Virginia slaveowners won a major victory when Thomas Jefferson's 1808 prohibition of the African slave trade protected the domestic slave markets for slave-breeding.
I haven't read the book, but I imagine they touched on the fact that by growing slave populations, southern states were literally manufacturing more political representation due to the Three-Fifths clause in the US Constitution. They bred more slaves to help politically safeguard the practice of slavery.