A preliminary survey line established by a land surveyor to approximate the location or direction of a property boundary before its exact position has been determined. In traditional land surveying, a random line is often run between two known or estimated points to establish an initial course that can later be corrected through additional measurements. For example, when surveying a large parcel of land, a surveyor may begin at a known property corner and run a random line toward another corner whose precise location has not yet been established. After reaching the intended endpoint or determining its position, the surveyor calculates the difference between the preliminary line and the true boundary. These measurements are then used to establish a corrected line that accurately connects the required points.
Random lines were particularly important in early American land surveys, including surveys conducted under the Public Land Survey System (PLSS), where surveyors often had to establish long boundary lines across difficult or unfamiliar terrain. Despite its name, a random line is not selected arbitrarily. It is a deliberately measured preliminary course used to help determine the correct alignment of a survey. In traditional surveying practice, the corrected course may be referred to as the true line, which represents the intended boundary between established survey points. Although modern surveying equipment, satellite positioning, and electronic measurement techniques have reduced the need for some traditional random-line procedures, the term remains important when interpreting historical survey notes, government plats, and older legal descriptions. A random line generally serves as a surveying reference rather than a legally established property boundary, unless other evidence or applicable law gives it that significance.
