The Wall Street Mill in Joshua Tree National Park was a complete and operable gold ore crushing mill featuring late-19th century two-stamp mill machinery. Consequently, the significance encompasses the mill machinery, the building which houses it, the well which supplied water for the mill's operation, and the well pump. It is the only gold ore crushing mill in the region that retains integrity. The complex included the mill, a well, a bunkhouse and an outhouse. The supporting buildings are largely ruinous.