Route 66 is remembered as the "Mother Road" and it still holds a fascination for a lot of people. There is a lot of online info about it - just Google Route 66. Travelers still choose to trace its path across the country, so some of the "artifacts" are still standing and some new ones have been added. Arizona seems to have more points of interest than California or New Mexico.
I don't drive anywhere that there are as many billboards as along I-40. I assume they are on Indian land. I haven't driven around Mt. Rushmore for years, but I remember the unending billboards along the roads there and was told they were on Indian land.
They pretty much say the same thing.
Although there are different stores advertised.
Some effort has been made to make the locations attractive to tourists.
Another tourist attraction is Petrified Forest National Park. I've been through it a couple times, enough.
Along the way, from New Mexico into SCalifornia there are many dinosaurs - realistic and cartoonish. There are in Holbrook, AZ.
Also in Holbrook is the Wigwam Motel which has been there forever. I don't know anyone who has stayed there, but someone must stay since it is still in business.
Outside each wigwam 'cabin' there is a vintage automobile - more atmosphere.