It heads south from the interchange and provides access to Kartchner Caverns State Park.

It continues to the east until curving towards the southeast near the overpass over the San Pedro & South Western Railroad line.

The highway continues to the southeast to its eastern terminus at a junction with SR 80 between Tombstone and Bisbee.

[1][2] The highway was designated in 1936, but constructed in the 1940s, and originally covered the route from Sierra Vista to US 80 near Bisbee.

SR 90 has a spur route, logged as two separate sections and located entirely within the city of Sierra Vista.

[3] The remainder of Buffalo Soldier trail acts as the western edge of Sierra Vista.

[3] On some satellite photographs, the spot where ADOT maintenance of Hatfield Street begins can easily be seen where the road has a sudden change in the pavement.