mi²

square mile

Areaexact by definition

The square mile is the area of a square one mile on a side, exactly 2,589,988.110336 m², which is 640 acres or about 2.59 km². It is the standard unit for the areas of American counties, land grants and survey sections. The factor is exact by definition.

1 mi² 2,589,988.1 m²
Where the unit came from

In the US Public Land Survey System, a section is one square mile and a township is six miles square, holding 36 sections. Much of the road grid west of the Appalachians follows those section lines, which is why rural intersections there tend to be exactly one mile apart.