Public Land Survey System

source: http://geology.isu.edu/geostac/Field_Exercise/topomaps/plss.htm

PLSS maps (Public Land Survey System) are used to define specific parcels of land (for ownership purposes). Land is divided into 6-square mile townships from a North-South line called the "Principle Meridian". These townships are then further divided into 1-square mile blocks and further divided into 1/4-mile squares. Numbers and letters (NE, NW, SE, SW) differentiate squares.