Correction Line
An east-west line in the PLSS established at regular intervals to correct for convergence of meridians toward the poles.
Detailed Definition
A correction line (also called a standard parallel) is an east-west line in the PLSS established at regular intervals (typically every 24 miles, or every four townships) to correct for the convergence of meridians as they extend toward the poles.
Why correction lines are needed: - Lines of longitude (meridians) converge toward the poles - Without correction, range lines would get progressively closer together moving north - Townships would become trapezoidal rather than square - Correction lines reset the 6-mile range width to maintain approximately square townships
How correction lines work: - A new baseline reference is established at the correction line - Range lines are re-measured from the principal meridian at the standard parallel - Township boundaries north of the correction line are measured from the new reference - This creates a slight jog or offset in range lines at each correction line
Effects of correction lines: - Sections along correction lines may be irregular (fractional) - Range lines do not align across correction lines (creating offsets) - Township boundaries along correction lines may have gaps or overlaps - Government lots may be used instead of standard aliquot parts for fractional sections
Spacing: - Standard parallels are typically placed every 24 miles (every 4 townships) - Some regions have different spacing depending on when the survey was conducted - The Manual of Surveying Instructions prescribes the procedures for establishing correction lines
Correction lines are an important feature of the PLSS that affects section sizes and legal descriptions, particularly for mining claims located near these lines.
Related Terms
PLSS
The Public Land Survey System, a method of subdividing and describing land in the United States using townships, ranges, and sections.
Principal Meridian
A north-south reference line running through an initial point, from which ranges are numbered east and west.
Base Line
An east-west reference line running through an initial point, from which townships are numbered north and south.
Section
A one-square-mile (640-acre) unit of land within a PLSS township, numbered 1-36 in a serpentine pattern.
Lot
In the PLSS, an irregular fractional subdivision of a section, typically found along township edges where sections are not perfectly square.