Montana/highway classification

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This is a proposal for standardized road classifications in Montana as part of a larger discussion about classification standards nationwide (United States/Highway classification). You're free to add on and edit the contents of this page.

This is a centralized page for rural Montana highway and other road classification.


We use several different metrics to evaluate the importance of every highway. These include, but are not limited to:

  • Traffic counts
  • Road quality for motor vehicles (e.g. number of lanes, average speeds, pavement)
  • Number and quality of alternate routes available
  • Whether the roads connect any populated locations of note or serve popular recreation areas

We do not copy any of the governmental ways of classifying highways (functional class, US vs state vs county route, etc.), but we do use them as guides to help with the particulars.


MDT Sources

Other Sources

OSM Wiki Sources

The Montana/Highways page gives an overview of MT highway network. While it lists mostly the "TIGER review status" (reviewing highway geometry, surface, names etc.) it also describes the classification used for different groups of highways so far.


Trunk routes

Corridor Endpoints Reason
US 2 ID to MT Eastern half is the best route from Kalispell to Minot ND. Western half is interesting: considering solely the United States I don't think it would qualify for trunk. But in border states it's necessary to consider Canada as well, and this is actually part of the best route from Kelowna BC to Kalispell. So that brings it up to trunk for me. I also would think the short section between US 93 and MT 40 should not be trunk; it still gets heavy traffic but functions more as a local street, while the US 93/MT 40 bypass is built more for through traffic.
US 93\MT 40 I-90 to Canada Route to Kalispell from the south, and from Calgary AB. Also includes the short MT 40 connector between US 93 and US 2 north of Kalispell.
US 87 Great Falls to US 2 Although signposted as a north-south route, this route actually runs more east-west in this area. It's part of the best route between Great Falls and Minot ND.
MT 3 I-15 to I-90 Best route between Great Falls and Billings.
MT 200 I-90 to I-15 Best route between Missoula and Great Falls. Although I could see the argument for US 12 through Helena being the better route, I disagree; the road quality isn't significantly different and the MT 200 route is quite a bit faster.
US 12/US 287 I-90 at Garrison to I-90 at Three Forks Fastest route to Helena from either the east or west.
US 20/US 191 ID to I-90 Route to Bozeman from the south.
MT 72/US 310/US 212 WY to I-90 Best route to all of the many central WY towns from most places in MT; also fills what would otherwise be a large gap without trunk roads.
MT 16/MT 200 I-94 to ND Best route from Billings to Minot ND.
US 212 I-90 to SD Actually a faster through route than I-90 through this area between Billings and Rapid City SD; most passenger car through traffic uses this bypass rather than staying on the interstate through WY.
MT 16 MT 200 to Canada The most important Canada/US border crossing for a very large distance between I-15 and US 52, and part of the best route between Regina SK and Billings.