Southern Pacific was a latecomer to Cajon Pass, being built 1966-67. Unlike the Atchison, Topeka & Santa Fe's line which was basically a way to gain entrance to the Los Angeles Basin from the east, Southern Pacific's Colton-Palmdale Cutoff was actually built as a shortcut from the SP's Sunset Route at Colton, California to the Tehachapi line at Palmdale, north of Los Angeles. This enabled the SP to completely bypass Los Angeles when appropriate. Having the advantage of more advanced earth moving techniques it was able to remain on the east side of Cajon Pass without ever crossing the Santa Fe's line. In this slide looking south the Santa Fe's westbound (downhill) line is at the left.
