In what direction does a principal road route, such as I-71, run?

A principal road route like I-71 runs North/South, which is a characteristic of odd-numbered Interstate highways in the United States. The numbering system for Interstates dictates that even-numbered routes run East/West while odd-numbered routes run North/South. Therefore, I-71, being an odd-numbered Interstate, confirms that it traverses in a North/South direction. This systematic approach helps drivers understand navigation and route orientation across the highway network. As a result, knowing that I-71 runs North/South is essential for proper navigation and planning travel routes.