Controversy regarding the northern border of the Tehachapi Mountain Range
This entry lists the northern border of the Tehachapi Mountains as being the present day Tehachapi Pass along HWY 58. This is accurate for Tehachapi Pass east of the City of Tehachapi. However, this is not true for the Tehachapi Pass as it travels west to Bakersfield.
The western route used by both the railroad and Hwy 58 is not the historic pass referenced by early geographers. Rather, it was the old Butterfield Stage Coach Route that traveled through Tehachapi, Brite, and Cummings Valley. The route followed the north ridge of Chanac canyon, which is located near Stallion Springs, and is now known as Commanche Point Road and/or the Sheeptrail. This pass terminates in the San Joaguin Valley southeast of the City of Arvin.
Therefore, the Tehachapi Rail Loop is actually located in the Sierra Nevada, as is the Old Monolith Cement Plant and Bear Mountain.
Wikipedia's map of the Sierra Nevada accurately depicts the southern limit of the Sierra, which is also the northerly boundary of the Tehachapi Mountains.