The Public Land Survey System (PLSS) is a way of subdividing and describing land in the United States. The PLSS typically divided land into 6-mile-square townships. Townships were subdivided into 36 one-mile square sections. Each section covered 640 acres. Sections were further divided into quarter sections, quarter-quarter sections, or irregular government lots. Each township is identified with a township and range designation. Township designations indicate the location north or south of a base line, and range designations indicate the location east or west of the Principal Meridian.
Due to such things as survey errors, poor instrumentation, or difficult terrain it is common for actual sections to differ from the PLSS ideal. Such factors sometimes result in sections that are far from square, or that contain over or under the standard 640 acres. The Bureau of Land Management (BLM) is the federal government’s official record keeper for the PLSS data.