Doug,
Not much. West of Floyd Hill old Hwy. 6, and now a frontage road, is pretty much on the grade, except for just outside and through Idaho Springs. In town the location of the grade is still there but you wouldn't know it if you didn't know what you were looking at. West of Idaho Springs the construction of the interstate highway and frontage road pretty much changed the whole valley, including the creek bed and railroad route. If you drive west of Idaho Springs on the frontage road there are a few pieces of the grade that can be seen. At Dumont the original location of the depot, RR grade, creek bed and in fact pretty much the entire town is where the highway is now. The depot was saved and moved up the hillside to the south. At Empire Junction the grade goes through private property where the depot still exists in its original location but heavily remodeled into a residence. It also goes through a CDOT maintenance yard where over the years ties and other RR junk have been unearthed. Due to highway construction and flood damage, between Empire Junction and Georgetown virtually nothing is left. In Georgetown the grade is visible as it diverged from the spur to the depot before it is encrouched upon by several houses and a mine dump that buried the grade after the RR was abandoned. Just above the end of the main street in Georgetown (actually 6th. St.) is an impressive rock wall that supported the grade as it climbed out of town toward the Loop and Silver Plume. West of Silver Plume there actually are a few pieces of the old grade to Graymont that can be seen. There is also an interesting beginning of a grade that would have eliminated the switchbacks on the Argentine Central. I don't know if this was started after the completion of the AC or if this was a route that was started before they decided begin the RR in Silver Plume and use switchbacks. Out of Graymont (or Bakerville as it is known today) you can drive up and see the portal of the Atlantic & Pacific Tunnel which was to be a rail connection to the Keystone Branch on the other side of the divide. I've seen the portal of this tunnel but have no idea how they were going to get the railroad up there as it is considerably above the Clear Creek valley floor.
Hope you find this helpful. This is an interesting area to explore and I did a lot during the 20+ years I lived there.
Phil
