East of Alamorio, SR 115 turns due north again, and intersects CR S26.

After a few miles, the highway turns due west, reaching its north end in Calipatria at SR 111.

[8] The routing from Brawley to Calipatria was added to the state highway system in 1933;[9] following the completion of the road from Yuma to San Diego, increased tourism and growth led to the development of more highways in Imperial County, and the construction of the system was expected to aid in future growth, according to the Los Angeles Times.

[11][15] By 1961, the highway continued just west of Holtville to an intersection with US 80 (later I-8), where it ran concurrently with US 80 briefly before heading south to a junction with SR 98 in Bonds Corner.

[21] Except where prefixed with a letter, postmiles were measured on the road as it was in 1964, based on the alignment that existed at the time, and do not necessarily reflect current mileage.