Township-Range-Section

In the United States theLand Ordinance of 1785 introduced a system for keeping track of land titles, technically known as The United States Public Land Survey (USPLS), and commonly referred to as Township-Range-Section' system (TRS). The TRS covers all US land that was not settled by the time of the official government survey. Most areas along the east coast were settled well before its introduction, and so are not covered. Some states were just beginning to be settled when the required survey was conducted, and as a result small porions of those states are not covered by the TRS.

Within areas covered by the TRS, the system was used to describe locations of land purchases. There are four parameters used in these records to describe these locations:
 * Meridian,
 * Township,
 * Range and
 * Section number.

Meridian. This is the key designation that locates the general area in which a parcel lies. it corresponds to a line of longitude, and no TRS designation is complete without designating the meridian which serves as a reference line against which the Towships, Ranges, and Sections are designated. The position of the principal meridian for any area is largely historical and arbitrary. There is no great significance as to which line of longitude was chosen to serve as the meridian in any given area, though sometimes State boundaries coincide with the meridian's used to describe land titles within the state. Each meridian runs north and south along as line of longitude; there is a 'base-line' that runs east and west with latitutde, that is associated with each meridian. Which line of latitude was chosen as the base-line is, like the meridian, largely arbitrary.

Township.  Townships lines occur at 6 mile intervals east and west of the north south meridian. The areas in between the township lines are designated with whole numbers, starting at 1.

Range. Similar to the Township lines, range lines also occur at 6 mile intervals north and south of the east-west base line. Range values are also designated with whole numbers starting at 1

Sections. The township lines and the range lines create a grid of 6 by 6 mile squares called Townships. Each such Township is subdivided into 36 sections made up (usually) of 1 by 1 mile squares.