[Southside_Chicago_Republican]

Not knowing the lay of the land there, I hadn't thought of that, although it did seem that he was in a hurry to put some distance between himself and her.

But others have thought about it in some detail. According to Wikipedia:

Webb did not intend the song to be geographically literal. "A guy approached me one night after a concert [...] and he showed me how it was impossible for me to drive from L.A. to Phoenix, and then how far it was to Albuquerque. In short, he told me, 'This song is impossible.' And so it is. It's a kind of fantasy about something I wish I would have done, and it sort of takes place in a twilight zone of reality."

[Fiji Hill]

If Glen was starting from LA, he would most likely go through Flagstaff. If he went through Phoenix, he would have to proceed east on Rte. 60, a narrow two-lane highway through the mountains and eventually pick up Rte. 66 somewhere west of Albuquerque.

Texola, just over the Oklahoma line, is about 1200 miles from LA. I drove about the same distance in a day, from LA to Boulder, Colo., but it was in a modern car and mostly over Interstate freeways going abut 80 mph most of the way. You couldn’t do that in 1967.