For Pete, and anyone else. Here are the extra verses I recall hearing on an LP in the 1970s. Damed if I can remember by who. I'm just one line short!

"If you're in the mood to see the Coast
Take the west road it's the best road
Really the most
Get your, etc

While driving throught Ohio check your spare
Cos soon you'll hit that famous thoroughfare
Get your kicks, etc

Bridge:
"South of the Great Lakes
(Sounds like) You feel up the pancakes (?)
The very dear Missouri will/might stimulate your appetite
See Amarillo, etc"