Historis US 6 in Palmdale, CA

[M3100]

Here's a pic from December 2014: a Historic US 6 shield, on 6th Street East in Palmdale.  This is a couple blocks south of the Palmdale Transportation Center.  This may be an earlier alignment before the Sierra Highway was built.

[Max Rockatansky]

6th Street is shown on the 1935 Division of Highways Map of Los Angeles County as the route of CA 7 (future US 6) in downtown Lancaster.  It looks like CA 7 jogged over the Southern Pacific tracks at Avenue O.  Interestingly this would have been the historic route of CA 138 also:

http://www.davidrumsey.com/ll/thumbnailView.html?startUrl=%2F%2Fwww.davidrumsey.com%2Fluna%2Fservlet%2Fas%2Fsearch%3Fos%3D0%26lc%3DRUMSEY~8~1%26q%3DCalifornia%20division%20of%20highways%20Los%20Angeles%26sort%3DPub_List_No_InitialSort%2CPub_Date%2CPub_List_No%2CSeries_No%26bs%3D10#?c=0&m=0&s=0&cv=0&r=0&xywh=6580%2C2162%2C534%2C881

[M3100]

Thanks for looking that up.  At some point they added the Sierra Highway extension that now crosses the track on an S-curve, near the present-day station.

[Max Rockatansky]

More than likely the answer is buried in a CHPW volume.  If I get some time I'll have a look but they can be found here:

https://archive.org/search.php?query=california%20highway%20and%20public%20works