Inland Navigation Rules
In the United States there are actually two sets of regulations that govern navigation. The Inland Navigational Rules Act of 1980 became effective on December 24, 1981. These rules, more commonly known as the Inland Rules govern many rivers, lakes, harbors, and inland waterways. The 72 COLREGS, also known as the International Rules, govern open bodies of water in which foreign shipping traffic is possible. The boundaries between where the Inland Rules and the International Rules apply are displayed as Demarcation Lines on navigation charts. These boundaries are commonly identified on charts as purple dashed lines containing the label COLREGS DEMARCATION LINE.