California State Route 138

State Route 138
Map of southern California with SR 138 highlighted in red
Route information
Maintained by Caltrans
Length	105.376 mi[1] (169.586 km) SR 138 is broken into pieces, and the length does not reflect the SR 14 overlap that would be required to make the route continuous.
Existed	1934–present
Tourist routes	Rim of the World Scenic Byway
Major junctions
West end	I-5 near Gorman
Major intersections	CR N2 near Sandberg SR 14 from Lancaster to Palmdale CR N6 near Pearblossom SR 18 near Llano SR 2 at the Piñon Hills–Phelan border I-15 at Cajon Junction
East end	SR 18 near Crestline
Location
Country	United States
State	California
Counties	Los Angeles, San Bernardino
Highway system
State highways in California Interstate US State Scenic History Pre‑1964 Unconstructed Deleted Freeways
← SR 137 → SR 139

State Route 138 (SR 138) is an east–west state highway in the U.S. state of California that generally follows the northern foothills of the San Gabriel Mountains and the western Mojave Desert. The scenic highway begins in the west at its junction with Interstate 5 located south of Gorman in the Sierra Pelona Mountains, continues eastward through the Antelope Valley and Cajon Pass, to its junction with State Route 18 in the east, located in the San Bernardino Mountains south of Crestline.

Except for the western two miles (3.2 km) of the route between Interstate 5 and just east of Gorman Post Road and a segment shared with State Route 14 between Avenue D in Lancaster and Palmdale Boulevard in Palmdale, it is all a mostly undivided two-lane surface road. The remaining section of the Ridge Route, California's first highway connecting the San Joaquin Valley to the Los Angeles Basin, ends at Route 138 near Gorman.