[3] Mary Hallock Foote's husband, the civil and mining engineer Arthur De Wint Foote, became manager of Grass Valley's North Star Mine after building its powerhouse in 1895.

In 1911, O'Brien, Foote & Associates purchased the Tightner Mine in Alleghany.

[5] The road was significant during the period of 1913–1924 both as an engineering accomplishment and as an improved transportation route.

[8] Italian stonemasons built the high stone embankment walls prevalent on the tight curves above the Middle Yuba River.

The Tightner Mining Company and Sierra County jointly built the Sierra County portion of the road, which skirts Kanaka Creek and the Lafayette Ridge on the road's southern side, but does cross Blue Ravine and Rapps Ravine.