Hill City: The climb begins. Less than a mile outside the Hill City Yard, the Black Hills Central's "1880 Train" begins its ascent up Tin Mill Hill. This is perhaps a 1/2 mile section of very steep and curving track with grades that run 4-6%. It is some of the steepest track on which you'll see a rod engine anywhere in the US. On virtually every trip, the Fireman takes advantage of the approach to this grade crossing to sand the flues of his oil-fired locomotive. This procedure removes accumulated soot, which negatively impacts heat transfer. The sanding operation produces probably the best plume you'll see all day, just as she crosses Old Hill City Road.