With the development of cities, the pastoral meat industry was displaced. Meat animals were increasingly separated from those who ate them. As meat is very perishable—and refrigeration did not become available until the nineteenth century—animals had to be brought to the cities for slaughter. Herds of cattle and sheep were driven along the highways, from pasture to polis. In the eighteenth century, in England, even turkeys found their way to market on their own two feet. Pigs were not as easily driven, so they went to market on wagons.