State Route 138 is mostly a rural two-lane highway between I-5 and State 14. It passes through a rather flat section of the Antelope Valley area of the Mojave Desert. Near 140th St West, State 138 passes near the Antelope Valley Poppy Reserve, which can turn a beautiful orange during a good bloom. The reserve is also along an old alignment of 138, having originally followed Lancaster Road before using Ave D in the late 1940’s. Once it reaches State 14, it becomes cosigned with 14 until Palmdale, where it heads east toward the 15 and Crestline. It is quite heavily traveled from Palmdale to I-15.
Plans are being laid to widen the route from Palmdale to I-15 from two lanes to a four lane conventional highway (no control of access). A direct connector (flyover) ramp is also planned to better connect 138 east to 18 east at Antelope Junction. Earlier plans (1960’s) called for 138 to be upgraded to a full freeway from I-5 to I-15. That freeway was to be called the Metropolitan Bypass Freeway. Only a short connector was built at the I-5 junction. The California Poppy Reserve is also located near 138 on the west end of the Antelope Valley.
East of I-15, State 138 becomes a very twisty mountain road. Portions have been realigned, mostly around Silverwood Lake. One of the twistiest sections, between I-15 and Summit, will be realigned and bypassed in the next couple of years (2016). The road ends at its junction with State 18 at what I call the “Interchange in the Sky” at Mt Anderson near Crestline.