If you’re driving with someone, a good neck pillow for the passenger so they can rest when you trade off.
Back pillows for everyone.
Be sure to text someone everytime you make a stop for gas and let them know where you are, where you’re headed next and approximately when you’ll get there - that way if you don’t text they’ll know to call and have an approximate location to look for you.
building off the last item, add air tags in your car and belongings that you can track and also share the account info with trusted family/ friends to help locate you in the event something goes wrong
Bring little orange cones in case you break down or have to fix a flat. Safety first - vest doesn’t hurt either.
Download music or audio books as you won’t get reception in many areas.
good pair of sunglasses and a backup pair
extra prescription meds - split between two bags in case you lose one
cut proof and RFID blocking bag of some sort put your wallet, phone, keys in when you stop - fanny packs are great but not for everyone. Find one that works for you whether it be a backpack or something else. Travelon is a great brand.
stop for gas each time you get to half a tank. I know it sounds like overkill but you never know if you’ll be diverted for a road closure through the heartland with no services for 100+ miles. It never hurts to have a full tank, give yourself a stretch, bio break and caffeine refill.
I’ve done road trips with a partner and solo - you’ll have s blast. Make sure you’re safe first and foremost. Do tons of research before you go so you hit all the spots you’re interested in and have backup plans in case places are closed. Take some pictures but also just enjoy your journey.