Hidden Highway

Lincoln Highway logo taken form the Association site.

The old Lincoln Highway was the first official transcontinental highway made specifically for automobiles in the US, spanning from New York City to San Francisco. Many states have the historic route marked along the current streets and highways that the many versions of the route took over the years. Most of the original and updated routes can still be traveled in the eastern portion of Utah on modern roads. The western half, on the other hand, is another story. 

You can see an interactive map of the routes the highway took on the official association site that took many years to painstakingly research the original routes. Coming from the eastern side of Utah, you can trace the path of the Lincoln Highway by going along the current routes of I-80 to the I-84 loop, then to the current I-15 route south to SLC where it branches off west to the current Highway 171, and back to I-80 in Magna. It then follows either highway 138 and 196 through Grantsville, or Highways 36 and 199 through Tooele until reaching Dugway Proving grounds. 

At this point you can no longer follow the original route, as almost the entire rest of the original route lies within the restricted area of the Dugway Army Base until it meets up with the original Pony Express Road. 

Pics taken form the Atlas Obscura site.

As far as I know, there are no major historical markers for the Lincoln Highway in Utah other than the one that is unable to be visited by the public because it is inside the Dugway restricted areas. Just off the area containing the major chemical labs, about 12 miles within the main gate, there is a small monument. Made by the National Register of Historic places it stands near an unassuming little wooden bridge that is over 100 years old, one of the only original remaining structures created in 1918 for the highway. Now with it's only visitors being members of the Army and other security authorized personnel are allowed to visit it, though to be fair, like most things I post, the history is usually far more interesting than the place itself. 

Feel free to visit the Official Lincoln Highway Association site for more detailed info on the history of the highway.