At one time, the term back forty represented the land of least monetary value on a piece of property—the section farthest from the house or road, the piece least desirable and last developed, the forty acres Andrew Johnson had in mind when he refused to give freed slaves “forty acres and a mule.” It is property previously untilled and unlimed, the hardest to cultivate. The term originated from the rectangular survey method devised by Thomas Jefferson and used by the federal government, wherein a section was one square mile, or 640 acres. A sixteenth of a section was—and still is—forty acres. In current parlance, back forty designates the cast-off or forgotten terrain that nonetheless deserves the same protection and consideration as more obviously valuable conservation projects. For instance, the Environmental Defense Network’s “Progress from the Back Forty” project promotes stewardship of the often-neglected portions of private land.