What is the term for the main imaginary line running east and west used in land surveying?

The main imaginary line running east and west used in land surveying is referred to as a base line. In the context of the rectangular survey system (also known as the Public Land Survey System), base lines are essential for defining the boundaries of townships and ranges. Along with meridians, which run north and south, base lines create a framework for dividing land into parcels.

Base lines serve as reference points to measure and describe the location of land parcels. Each township is typically six miles square and is divided into sections, and the base line helps establish the horizontal boundaries of these townships. Understanding the function of base lines in land surveying is crucial for accurately interpreting legal descriptions of properties and navigating the complexities of land ownership and transactions.

The other options relate to different concepts in land measurement. For example, latitude lines refer to imaginary horizontal lines that measure distances north or south of the Equator, while longitude lines measure distances east or west of the Prime Meridian. Principal meridians are used in conjunction with base lines but run north and south.