Corner points are calculated for each Township, Section, and Quarter-Section using the coordinate data provided by BLM. These values are estimates only.
Earth Point gets its data from ESRI shapefiles supplied by BLM. Each Township/Range/Quarter polygon can have anywhere from eight to fifty or more points defining its perimeter. For each point, Earth Point calculates the interior angle and the orientation of that angle. If the angle is close to 90°, faces in the right direction, and is close a corner point of shape's bounding box, then the point is considered to be a corner point of the polygon itself. If a polygon is irregularly shaped, then it might not have all four corner points.