This is not only the longest highway in Montana, but the longest in the country as well, thanks to the massive size of our state.

Montana highway 200 goes for a long time! It is just shy of 707 miles long. The closet one to that is California's State Route (Highway) 1 which is 655 miles long. This highway starts at ID 200 near Heron in Montana then runs east near Fairview, Montana.

You can find the Clark Fork river alongside this at some points as well as the beautiful Blackfoot. This is a good scenic route to travel, and helps connect many small areas together. Many of us have traveled this road and can also say that unfortunately it can be very dangerous in the winter.

Wikipedia has a cool map as well.