Square Mile (mi²)
The square mile, or mi², is the area of a square one mile on each side, or 640 acres. Its history dates back to the mile, which originated in Roman times. The square mile became a set measurement in England. It is still widely used in the US and the UK for large areas, such as cities, counties, and parks. Most countries use square kilometers, but in English-speaking regions, the square mile remains common, especially in historical and legal contexts.
Square Inch (in²)
The square inch, or in², is the smallest commonly used unit of area in the imperial system. It is the area of a square with one-inch sides and equals 6.4516 square centimeters. It originates from the inch and has been widely used in engineering, technical drawings, and manufacturing. Today, it is still good for small things like screens, machine parts, and prints. Most countries now use square centimeters, but the square inch is still used in areas where the imperial system is prevalent.