A square perch, often referred to as a "square pole" or simply "perch," is an obsolete unit of land area measurement. It was historically used in some English-speaking countries, including the United States and the United Kingdom, for land surveying and property descriptions.
One square perch is equivalent to one square rod or one square pole. In terms of modern measurements, one square perch is approximately equal to 25.29285264 square meters (m²) or 0.00625 acres.
Like other obsolete units of land area measurement, the square perch has largely been replaced by more standardized systems of measurement, such as square meters and square feet, in modern times. It is rarely encountered in contemporary land transactions or legal documents.
A square mile (often abbreviated as sq mi or mi²) is a unit of area used primarily in the United States and a few other countries. It is defined as the area of a square with sides that each measure one mile in length. One square mile is equal to 640 acres.
In terms of the International System of Units (SI), one square mile is approximately equal to 2.58999 square kilometers (km²).
To provide some perspective, a square mile is commonly used to describe land areas within cities, counties, and states in the United States. It's a convenient unit for measuring larger land areas, such as the size of cities or counties.