The square mile (abbreviated as sq mi and sometimes as mi2)[1] is an imperial and US unit of measure for area. One square mile is equal to the area of a square with each side measuring a length of one mile.[2]
Square miles should not be confused with miles square, a square region with each side having a length of the value given. For example, a region which is 20 miles square (20 mi × 20 mi) has an area of 400 sq mi; a rectangle of measuring 10 mi × 40 mi also has an area of 400 sq mi, but is not 20 miles square.