Highways replaced several of the state's primary roads and other routes were renumbered in order to eliminate driver confusion between the two systems.
Previously, the primary road number was stenciled in black onto a telegraph pole over a band of yellow paint.
Often, the trails were not the most direct ways to travel between places and as a result, competing auto clubs would spring up to divert traffic from other routes.
[1] Starting in 1920, the Iowa State Highway Commission began marking these auto trails with primary road numbers in order to facilitate wayfinding.
Each of these auto trails were sponsored by dues-collecting associations that produced maps and other promotional materials for their routes.
[6] While the efficiency of wayfinding was greatly improved by the addition of route numbers, motor club officials wished for the names of their highways to not be forgotten.
[7] Hayes got his wish as the automobile associations disbanded, motorists continued to refer to the routes with their trail names.