Arterial highway signs would be similar to business route shields for interstates.

The idea came to me after seeing the uniform highway numbering system proposed by Mike the Actuary. It was a great idea, as it created a uniform grid for major US highways that was consistent for expressways and other major highways as well. As you know, the current US highway system is based on one grid and the Interstate highways are based on a reversed grid. The result has been that the US system has been relegated to a background status, with many major routes decommissioned [as in the case of US 66 and 99] or becoming a secondary route [as route 11 is to I81].
Copyright 2007, Kirchman Associates