What is the primary survey line running east and west in the rectangular survey system?

In the rectangular survey system, also known as the Public Land Survey System (PLSS), the primary survey line that runs east and west is designated as the base line. These base lines serve as foundational reference points for determining the location of townships, which are one of the core components of this survey system. Each base line intersects with a principal meridian, which runs north and south, thereby creating a grid system for mapping and subdividing land.

The base line allows surveyors to create townships that are typically six miles by six miles, providing a structured method for land description and ownership. Understanding this system is crucial for anyone involved in real estate, as it forms the basis for legal descriptions of properties and helps delineate boundaries. The identification of land parcels begins from the intersection of base lines and principal meridians, leading to the subdivision into ranges and sections, which are the smaller units of land used for selling and describing real estate.