Land Measure

An acre is a traditional measure of land. Land was once measured in England in furlongs, which are defined as one-eighth of a mile (660 feet, the length of a furrow that an ox could plow before needing a rest) by a rod (16.5 feet, the width of a field a furlong wide that an ox could plow in 10 passes). A farmer and his ox could plow a field a furlong by four rods (66 feet) in a full day. This was defined as one acre (43,560 square feet). Thus a piece of land a furlong by a furlong would be 10 acres. A square mile would contain 64 of these blocks a furlong square, or 64 acres  and this was called a section. A quarter section would then be 160 acres. The United States was blocked off in sections as the west was opened to farming.

Incidentally, horse races are still measured in furlongs, and one can see races at distances such as six furlongs, a mile and an eighth or a mile and a quarter.

Race horses passing a furlong post