The square mile was to the 19th century as far as a mile common European and North American surface measure. Its sheer scale was different due to the different lengths miles from country to country.
A unit of square mile used in German-speaking countries until the 19th century equivalent to an area of about 55 square kilometers (compare with mile).
As a square mile it is applied in the Imperial measurement system and in the 21st century, especially so in the United States. A square mile is where the area of a square with an edge length of each 1 mile ( " statute mile" in contrast to nautical mile ). This area corresponds to the equivalent 2.589988110336 km ², that is almost 259 acres.
The abbreviation for square mile in English speaking countries is sq mi or mi ².
1 mile = 1760 yards = 5280 feet = 63360 inches = 1609.344 meters
1 square mile = 640 acres = 3.0976 million square yard = 27.8784 million square feet = 4,014,489,600 square inch = 2589 988.110 336 m²