Pigs make piglets!

The same quality that makes feral pigs a problem—prodigious fecundity—has delighted farmers. Cows, goats, and sheep provide milk, a bountiful and consistent source of protein. Oxen pull plows and carts, and sheep are shorn for wool. Pigs do not pull plows; they give no milk and grow no wool. Pigs produce only one thing: more pigs. Many, many more pigs.

Mark Essig, Lesser Beasts: A Snout-to-Tail History of the Humble Pig (New York: Basic Books, 2015), Prologue

People have valued meat through history . . .

Nearly every society has placed a high value on meat. . . . Although humans can satisfy all their nutritional needs by eating plants, most of us prefer not to. Instead, we feed plants to animals and then eat the animals, and we do not seem to mind that this process is costly and complicated. People have fought wars, conquered lands, destroyed landscapes, and exchanged great wealth to satisfy their deep hunger for meat. When it is scarce—and in large societies meat has been scarce until recent times—only the wealthiest eat it. When poor people begin to earn a bit more money, they spend it on meat. "Those who could, gorged themselves," one historian has written of early modern Europe. "Those who couldn't, aimed to."

Mark Essig, Lesser Beasts: A Snout-to-Tail History of the Humble Pig (New York: Basic Books, 2015), Prologue (quoting Eugen Weber, A Modern History of Europe (New York: Norton, 1971), p. 202)

Pig drives!

Think of it: pig drives! Like cattle dries, only stranger! Who knew a pig could walk that far or would travel in the desired direction? . . .

Mark Essig, Lesser Beasts: A Snout-to-Tail History of the Humble Pig (New York: Basic Books, 2015), Prologue

A few farmers from Lexington, Kentucky, walked their hogs through the Cumberland Gap and all the way to Charleston, South Caolina, distance of more than five hundred miles.

. . .

Because droving was a decentralized trade, it's impossible to know its full scale. It is clear, however, that hog drives were at least as significant as the more celebrated cattle drives. The largest cattle drives, from Texas to Kansas, involved as many as 600,000 cattle a year, but they lasted just fifteen years or so. Hog droving, by comparison, involved hundreds of thousands of animals during peak years and on some routes lasted nearly a century. From Kentucky alone, as many as 100,000 hogs per year were driven east to Richmond, Baltimore, and Philadelphia.

Id., ch. 12.