To keep range lines as nearly as possible six miles apart, how often is a correction line made?

In the context of the Public Land Survey System (PLSS) in the United States, correction lines are employed to maintain accurate measurements of land due to the curvature of the Earth. While township and range lines are typically spaced six miles apart, the curvature of the Earth means that over long distances, these lines would otherwise become skewed.

To mitigate this issue and keep the range lines approximately six miles apart, correction lines are established every 24 miles. This ensures that the measurement for properties and land parcels remains consistent and accurate across the surveyed area. As corrections are needed, these lines adjust the survey framework, allowing the grid system to function properly despite the Earth's curvature.

This methodical adjustment every 24 miles is critical for mapping properly and preventing cumulative errors in land measurements, which is a fundamental principle in land surveying.