In
U.S. land surveying, a section is an area nominally one
mile square, containing 640
acres (2.6 km²). Nominally, 36 sections make up a
survey township on a rectangular grid. As the townships are based on
meridians (of
longitude) which converge towards the north pole, some sections which vary slightly in size are necessary to compensate. These unusually sized sections generally occur at the northern- or western-most edges of townships.
See more at Wikipedia.org...