The Quartz Flat rest area is about nine miles south of Superior, MT, the nearest town of any size. This is a typical Montana State rest area, with running water in the rest rooms and several picnic pavilions scattered about in a large grassed area under mature coniferous trees. The washrooms close in the winter, explaining the porta-potties at the back of the rest area.
An interesting Montana Historical Highway Marker can be found in the middle of the rest area. Text from the marker is below. The Mullan Trail, built in the 1850s, ran through this valley on its way from Fort Benton, MT to Fort Walla Walla, WA.
A WONDERFUL PIECE OF ENGINEERING:
THE BIG SIDE CUT
The Mullan Road is carved into the face of the mountains high above the Clark Fork River west of here. Lieutenant John Mullan tried to keep his wagon road as close to the river as possible. But when his work crews ran up against a mountain spur that reached all the way to the edge of the river, he was forced to seek an alternate route. Mullan later wrote that "to make this six-mile cut through rocky spurs was an undertaking that I almost feared to attempt." On May 10,1860, he assembled his entire workforce of 150 citizens and soldiers at the west side of the spur. For the next six weeks, his men dug, whittled, and blasted their way up the mountain side to an altitude of a thousand feet above the river. A premature explosion while clearing a path through the rocks wounded one man and severely stunned another. When completed in June 1860, the Big Side Cut segment was the most awe-inspiring of the entire 624-mile Mullan Road. A traveler wrote of the Big Side Cut in 1862 that it was "a narrow wagon track which left no room for careless or uncertain driving."
From the Montana Historical Highway Marker