The distant, Indo-European root of the word acre did not mean the measure of a place. It meant movement, speciﬁcally the movement of ﬂocks driven over open ground. As the word evolved, it came to indicate any untended land. Finally, an acre became the abstract measure laid over that land to commodify it. The evolution of acre from open commons to private property took at least a thousand years, but by the twelfth century an English acre was a unit of land that a man and a yoke of oxen could plow in a day. This was later ﬁxed by custom and statute in the United States as a square of land 208.7 feet by 208.7 feet (43,560 square feet or 4,840 square yards). For easier estimation, an acre is about the same area as an American football ﬁeld, excluding the end zones. In the West’s short-lived cattle economy of the open range in the mid– nineteenth century, acres of land hardly mattered, there were so many of them. Acres weren’t for measuring but for bragging.