Here is a list of the links I’ve gathered on long-distance biking 🙂
https://www.adventurecycling.org/ Seems to be the biggest association, many maps and tours !
Examples of people who have done this transamerica trip solo (or duo) before :
Physical preparation :
What to see in each state :
Motel 6 map (10% reduction being adventure cycling member) :
Many links, I have yet to dig here :