enacted in England, and subsequently the United Kingdom, by acts of: Edward I Edward III Henry VIII George IV Queen Victoria – the British Weights and Measures Act of 1878 defined it as containing 4,840 square yards. Historically, the size of farms and landed estates in the United Kingdom was usually expressed in acres (or acres, roods, and perches), even if the number of acres was so large that it might conveniently have been expressed in square miles. For example, a certain landowner might have been said to own 32,000 acres of land, not 50 square miles of land. The acre is related to the square mile, with 640 acres making up one square mile. One mile is 5280 feet (1760 yards). In western Canada and the western United States, divisions of land area were typically based on the square mile, and fractions thereof. If the square mile is divided into quarters, each quarter has a side length of mile (880 yards) and is square mile in area, or 160 acres. These subunits would typically then again be divided into quarters, with each side being mile long, and being of a square mile in area, or 40 acres. In the United States, farmland was typically divided as such, and the phrase "the back 40" would refer to the 40-acre parcel to the back of the farm. Most of the Canadian Prairie Provinces and the US Midwest are on square-mile grids for surveying purposes. Legacy acres Customary acre – The customary acre was roughly similar to the Imperial acre, but it was subject to considerable local variation similar to the variation in carucates, virgates, bovates, nooks, and farundels. These may have been multiples of the customary acre, rather than the statute acre. Builder's acre = an even or , used in US real-estate development to simplify the math and for marketing. It is nearly 10% smaller than a survey acre, and the discrepancy has led to lawsuits alleging misrepresentation. Scottish acre = 1.3 Imperial acres (5,080 m2, an obsolete Scottish measurement) Irish acre = Cheshire acre = Stremma or Greek acre ≈ 10,000 square Greek feet, but now set at exactly 1,000 square metres (a similar unit was the zeugarion) Dunam or Turkish acre ≈ 1,600 square Turkish paces, but now set at exactly 1,000 square metres (a similar unit was the çift) Actus quadratus or Roman acre ≈ 14,400 square