Bitterroot National Forest

3,457 miles of road and motorized trail here are open to vehicles today. The Forest Service is rewriting the rule that decides which ones, and 1,185 miles of this forest’s motorized trail have no mapped location in the agency’s national route data.

This forest’s own boundary on the USGS topographic map.

Motor Vehicle Use Maps

Bitterroot National Forest

The agency’s national route data maps 1,759 miles of road and 511 miles of motorized trail open to vehicles on this forest. Below is what each class of vehicle may use, and where that data runs out.

1,759road miles with a mapped locationmeasured from the lines

511trail miles with a mapped locationmeasured from the lines

58%of mapped miles are seasonalnot open year round

1,185trail miles with no mapped locationof 1,691 the agency records

Hover any line for what it is and who can drive it

Loading routes…

Roads in gold, motorized trails in green, the forest boundary dashed, on the USGS topographic base. Zoom in for road numbers and names. Tap a vehicle type and the routes it may not use go grey. The lines are simplified for drawing; the forest's official Motor Vehicle Use Map is the legal one.

The figures, from the agency’s own data

What each vehicle class can use

These are miles where the Motor Vehicle Use Map affirmatively designates the class as open. A blank value in the source data means the class is not designated on that segment. It is not the same as a closure, and no closed figure is published here because the data cannot support one.

Vehicle class	Road miles	Trail miles	Total
Passenger vehicle	1,496	0	1,496
High-clearance vehicle	1,496	0	1,496
Motorcycle	353	502	855
ATV	353	350	702
Other wheeled OHV	353	344	697
4WD over 50 in	92	0	92
2WD over 50 in	92	0	92
Tracked OHV under 50 in	92	0	92
Other OHV under 50 in	92	0	92

What the national data holds for this forest

The national dataset holds route records for every ranger district on this forest.

Ranger district	Road records	On the map	Motorized trail records	On the map
West Fork Ranger District	341	341	523	133
Sula Ranger District	279	279	275	112
Darby Ranger District	328	328	203	64
Stevensville Ranger District	123	123	155	26
District not named	2	2	4	3

Counts are records in the USDA Forest Service Enterprise Data Warehouse MVUM service, roads and trails layers, harvested 21 August 2026. “On the map” means the record carries geometry a map can draw. A district with no road records is not a district without roads; it is one the agency has not published to this dataset.

Why a route with no mapped location matters

A route on this forest is legal to drive only if it is on the forest’s Motor Vehicle Use Map. Every route the Forest Service designates gets a recorded length in its database; only some get a location anyone can pull up. A route with no location can’t be looked up in that data, can’t be proved legal from it, and can be left off the next map without anyone noticing. The proposal would make that next map the legal record.

1,185 miles of motorized trail on this forest, trails designated for ATVs, dirt bikes or side-by-sides, have no mapped location in the agency's national route data. Those routes are in the agency's route database with a length and, in many cases, live vehicle-class designations, but no location, so no map built on that data can show them. That is 70 percent of this forest's recorded motorized trail mileage. It is a count of that national data, which the proposal would make the legal record, and not an audit of this forest's own printed map.

This map is being rewritten, and comment is open

On 24 August 2026 the Forest Service proposed rewriting 36 CFR parts 212 and 261, the rules that produced this map. Today a route on the Bitterroot National Forest is closed to vehicles unless the forest studied it and put it on the map. The proposal flips that: open unless someone documents a reason to close it. It also removes the national rules that tell a forest supervisor to weigh damage to soil, water and wildlife, and conflict with other visitors, before a route goes in.

That change lands here in a specific way. The proposal would also make digital maps the authoritative source for what is designated, and 1,185 miles of this forest's motorized trail have no mapped location in that data at all. A route with no location is a route that’s hard to defend, hard to prove you may ride, and easy for the next map to leave out.

Public comment ran through docket FS-2026-0100 on regulations.gov until 23 September 2026. Comments that name a forest and say what the writer knows about it are the ones the agency has to answer. You know this one.

Comments closed 23 September 2026

Write your comment about the Bitterroot National Forest Talking points and a starter comment What the rule change does

Three minutes, in your own words. Your letter carries this forest's 1,185 miles of motorized trail that have no mapped location in the agency's national route data, because a comment that names a place is one the agency has to answer.

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When the rule itself lands, we will tell you

One email when the Forest Service files the proposed rule, and when a comment window opens on the public lands you use. Nothing else.

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Method. Figures for Bitterroot National Forest from the USDA Forest Service Enterprise Data Warehouse MVUM service, layers 1 and 2, harvested 21 August 2026. "Mapped" miles are measured from published geometry. "Recorded" miles come from the agency's route-length attribute and exist whether or not the route has been digitized. The two are different measures and are never added together. This page is not a legal travel document; the official MVUM for this forest is.