The Public Land Survey System (PLSS) is a legal land reference system set up to facilitate disposition of the federal domain into private ownership. Most land transactions in the thirty states that use the PLSS are described using the township, range, and section method of describing property.
Most of Arizona was mapped using the PLSS system. There are some areas, such as major portions of the Navajo Indian Reservation that were not included in the PLSS. The initial point of reference for the PLSS in Arizona is the confluence of the Gila and Salt Rivers, southwest of Phoenix. From this initial point, the state is divided into four quadrants (A, B, C, and D) by a north-south meridian and an east-west baseline.
Each quadrant is subdivided into townships with each township typically being 36 miles square, or six miles to a side. Each township is designed as being so many Townships north or south of the baseline and so many Ranges east or west of the meridian.
Each township is divided into 36 equal parts called sections. Each section is one-mile square, or 640 acres. Each section can be divided into quarter sections of 160 acres apiece. Quarter sections are further divided into 40-acre quadrants, which are further divided into 10-acre quadrants. Each 10, 40, or 160 acre quadrant is designated as the northeast, northwest, southwest, or southeast quarter. A legal description of the 10-acre parcel depicted in the following diagram can be described as the southeast quarter of the northeast quarter of the southwest quarter of section 1 in Township 1 North, Range 1 East.