We just got back from finishing up a segment of the Great Divide in Montana which was closed for fires when we rode it the first time. We were dismayed to see that from Basin To Butte, the route takes the Interstate(the only piece of interstate on the entire route). We did some research on Google Earth and the topo maps and found a wonderful alternative, all on public roads which must not have been available when the route was originally put together.
The route is only a few miles longer, and is on smooth, quiet gravel roads. There is an easy divide crossing, shared with the Continental Divide Hiking Trail., and a nice forest service campground. While the existing route enters Butte via big-box land, this one comes into the historic district.
I wrote the mapping department that this would be a worthwhile upgrade. The route and GPS data can be found here:http://connect.garmin.com/activity/226203936