The part which remains today is a graded dirt road which crosses southeastern Riverside County and a part of Imperial County , beginning roughly 12 miles\/19km east of North Shore and ending about 14 miles\/23km southwest of Blythe for a total of 70 miles\/113km . Its remainder , a graded dirt road , traverses southeastern Riverside County and a part of Imperial County , beginning roughly 12 miles\/19 km east of North Shore and terminating about 14 miles\/23 km southwest of Blythe for a total of 70 miles\/113 km .