The curvature of the earth makes it impossible to superimpose a regular grid on its surface, as the meridians converge toward the North Pole. As the U.S. is in the Northern Hemisphere, if a section's or township's east and west sides lie along meridians, its north side is shorter than its south side. As sections were surveyed from south and east to north and west, accumulated errors and distortions resulted on the north and west lines, and north and west sections diverge the most from the ideal shape and size.