Starting from Plains, Mt. you head toward the Thompson River area.  Between there and Kalispell, Mt, you might have a thousand miles of trails to follow!  The entire area is honeycombed with logging roads.  On weekends, you're free of logging traffic and can enjoy the roads and resulting trails.

If you go to St. Regis, MT, ask the forest service where the river trail starts.  There's a trail that follows along the south side of the river and it goes for several miles.  This isn't a fun trail if you're timid on high places as the trail hangs out over the river bank for quite a long ways.  The trail is soft dirt in those portions with a high bank on one side so you're horse has to know how to stay on the trail and follow the horse ahead of him without trouble.  I wouldn't take a green horse, or a flighty horse on this trail.

Behind Frenchtown, Mt, there are many logging road trails you can follow.  It's great country to unload your horses and ride for miles.  In the Seeley-Swan area, it's the same way, you can go for miles on logging roads, and trails.

If you like to ride into the Bob Marshall Wilderness, go to Dupuyer, Mt.  From there take the road to the Swift Dam trailhead, it's 18 miles of gravel.  You'll have a most enjoyable ride into the Bob.  The trail starts out by climbing a small cliff behind the "dam" house, then it follows Swift Dam up the South Fork.  As you go through the Gorge, you can see rushing water way below you!  There's also a rock slide to cross.  After that, the trail is simple.
Donna