The highway leaves the observatory heading towards the southwest as it descends the mountain.

It eventually begins to make the turn towards the west, then the north, and finally the northeast.

The highway makes a turn towards the north once the terrain smooths out as it heads towards its northern terminus at SR 86.

In 1986, the Arizona Department of Transportation acquired the right-of-way needed in order to widen the road.

[3] The entire route is in Tohono O'odham Indian Reservation, Pima County.