Truck stops can be found in nearly every state across the country. National brand truck stops are not just a place for truck drivers to take a break; they also welcome RV travelers. You can usually spend the night free of charge at many of them. Truck stops are hoping that you will come in and purchase their goods.
Some truck stop chains that welcome RVs include: Flying J, Pilot Travel Centers, Travel Centers of America, and Rip Griffin Travel Centers.
Some of these stops will not just offer overnight parking, fuel, and food; they also offer free dump sites and convenience stores to stock up on supplies. Since the stores are geared for long haul truckers you may find some useful travel gear that you might not find in a regular store.
Some truck stops may even have showers and laundry services (for a charge of course).