This route followed the general path of MT 1, traveling from Opportunity through Anaconda and Philipsburg to Drummond.

The overall length of the routing was approximately 76 miles (122 km), and was generally an unimproved dirt road.

Also, the section of the highway near the town of Brown traveling to Stone had been graded, while the rest of the route remained unimproved dirt.

[7] By at least 1927, MT 1 had been rerouted, with an overall length of approximately 71 miles (114 km), and the portion of the highway traveling from Stone to its northern terminus had been graded.

[9] In 1934, the portion of MT 1 that traveled from modern-day milepost 24.190 to the Deer Lodge–Granite County border was reconstructed along its current route.

[12] Also, the portion of MT 1/US 10 ALT traveling from present day mileposts 9.426 to 9.940 was reconstructed along its current route.

[10] In 1964, the portion of the road traveling from the southern terminus to the junction with S-441 were reconstructed to the present day routing.