Any point along any roadway can be identified using a “Measure”. Starting at zero—like a ruler—as you move along the centerline of the roadway, the value increases.
This measure follows any curvature in the roadway. All roadways have a measure feature including state highways. However, state highways also have a different linear reference system called “reference points”.
Reference points are a much older type of linear reference system that is identified with physical mile-marker signs posted along the highway. Law enforcement will use a reference point in their crash report to identify the location on a state highway. Measures and reference points can easily be confused for one another, and it is important to understand which system is being used.
For example, on ND 1804 reference point 75.00 is located at Measure 72.91. The different values are due to many factors, such as historic changes in roadway alignment.