A parcel of property comprises 640 acres. A parcel of land is 1 square mile or 27,878,400 square feet in size. An acre is equivalent to 43,560 square feet. By division, a section contains 640 acres.
Using whole-acre measurements makes it easier to divide the property into halves and quarters, which is one reason for surveying land into sections of 640 acres. A quarter section of land, or 160 acres, could be subdivided into quarters, or a quarter-quarter portion of 40 acres, with no mathematical knowledge. In 1832, the smallest land parcel that could be obtained was a quarter-quarter section.