Spanning 7.9 miles (12.7 km), it connects the cities of Sunnyside and East Carbon in Carbon County with Horse Canyon Mine in Emery County.

State Route 124 begins near Horse Canyon Mine along the Book Cliffs in northern Emery County.

The route continues north along the base of the Book Cliffs, through Columbia Junction just west of Columbia, and finally takes a jog to the west just before ending at its intersection with SR-123 in East Carbon.

[5] In 1935, the portion from Sunnyside to Columbia was split off[6] and designated as SR-124,[2] which was extended south to Horse Canyon Mine in 1945.

[7] Since then, only minor legal description changes have occurred such as reversing the described direction from southerly to northerly, and replacing "via Columbia" with "through Columbia Junction" after the town of Columbia became part of newly incorporated East Carbon.