Nearby is one of two sites in Illinois that serve as the basis for all land surveys in the state. It is the point just northwest of Beardstown, where the 4th principal meridian intersects its base line.
Originally, land was measured by "metes and bounds." with known landmarks as points of references. Boundary lines were compass lines or natural boundaries such as stream. This system proved unsatisfactory since landmarks are changeable and compass lines can vary. In May 1785, congress adopted the "rectangular system" of land measurement. In each state or group of states one or more north-south principal meridians and one or more east-west base lines on the parallels of latitude are established at right angles to on another. These lines are determined by astronomical observation and numbered. The 3rd and 4th principal meridians intersect their respective base lines in Illinois and govern all land measurements in the state.
Parallel lines are calculated at six-mile intervals east and west through the territory of each principal meridian. These divisions, called ranges, are consecutively numbered in each direction from the meridian. Similar lines parallel to the base line mark divisions called townships. The six miles squares created by the intersecting lines form government townships.
The number and direction of the township and range line, such as range 2 west, township 3 north, locate any township in relation to its principal meridian. Government townships are broken down into 36 numbered sections containing 640 acres. Acres form the basis of most property identification.