The southern terminus of SR 85 is located at the United States-Mexico border near Lukeville in Pima County. From Lukeville to Why, SR 85 is designated the Organ Pipe Cactus Parkway by ADOT. SR 85 heads north from the border as a two-lane road, passing through the Organ Pipe Cactus National Monument. The highway leaves the monument boundary and heads to a junction with SR 86 in Why.