Bill from Springfield, IL on 6/28/2023 2:09:40 PM:
There are 4 tunnels all are north of Hill City (Milepost 60)
Tunnel A is at Milepost 72
Tunnel B is at Milepost 73
Tunnel C is at Milepost 76
Tunnel D is at Milepost 85 just north of Rochford
The link will give you a great map of the trail including elevations and those trail markers. mickelson-trail-map.indd (sd.gov)
Have a great ride.