The Mother Road... My parents and oldest sister traveled Route 66 West from St. Louis to California in 1954, ( "... with a trail of poopy diapers out the side window..." ) as my dad says. I spent many a happy hour " track - cracking " the old highway Right of Ways on foot & dirt bikes during weekend campouts in the 1970's & 1980's. I even found a way to ride from Cleghorn Rd. to Tiffany's Cajon Station ( remember ??? ), withOUT using I-15, on my non - licensed dirt bike. I used the storm drain that runs under the I-15 truck scales !!!
Several additions to the narrative :
1) The Santa Fe railroad bridges at Alray had the Southbound lanes filled in after Interstate 15 was opened. I have often wondered why -- perhaps they were the older 1930's bridges and in poor shape ? The Espee bridge from 1967 still has both sides open.
2) In addition to Route 66 realignments South of Cleghorn Rd., the Santa Fe mainline was also relocated between Cajon siding and Blue Cut after the 1938 floods. The South abutment of the old bridge over Cajon Creek @ Swarthout Cyn. Rd. is still there I believe. Traces of the original mainline were still there into the 1990's for anyone willing to crash through the brush.
3) Anyone remember the old Forest Service campground at Blue Cut ??? This area was once referred to as Cozy Dell, not to be confused with Dell Siding on the original 3% mainline between Cajon & Summit.
4) During my line driving days at CWX I would sometimes drive Route 66 Southbound from Cleghorn Rd to the Devore split, with a stop at Blue Cut to relieve myself on the old scale pad !!! ( For all the Old Truckers who wished they could... )