Today, we take for granted the various systems of numbered highways across the country and around the world. But, as with anything, it all had to start somewhere, and that somewhere was Wisconsin when it comes to numbered highway systems.
By the mid-1910s, the proliferation of "marked" highways was reaching crisis proportions. Countless automobile clubs, tire companies, oil companies and tourist associations erected signs along randomly-chosen routes. Sometimes these routes would veer far from the best or most direct path only to pass through a city which paid a fee to have the marked route run though the center of town. Wisconsin was home to many of these so-called "auto trails."
In 1917, the Wisconsin State Legislature enacted a law which prohibited the marking and posting of any "trails" within the state without prior authorization from the state. By 1919, there was only one such "trail," the Yellowstone Trail, marked within the state. (Various "auto trails" existed in other parts of the country through the mid-1920s, however.) As a replacement for the multitude of marked auto trails, the Wisconsin legislature, under Chapter 175, Laws of 1917, authorized the creation and signing of a numbered highway system, with the State Highway Commission as the overseeing agency.
By late 1917, with all surveys and field reconnaissance completed, the State Highway Commission laid out a system of 5,000 miles of numbered state trunk highways on paper. During one week in May of 1918, all route designation signage was erected and Wisconsin became the first in the world with a signed system of route-numbered highways. Michigan, Wisconsin's neighbor to the east, adopted a similar highway signing plan later in 1918.
Since then, every state in the U.S., each Canadian province and almost every foreign nation around the world has laid out similar systems of numbered highways. The various iterations of the Wisconsin State Trunk Highway Marker can be seen on the right edge of this page. While it has undergone several transformations over the past eight decades, the familiar "Wisconsin triangle" is still there, guiding motorists to every corner of the Badger State.