If you are a Good Sam member they have a trip planner. Layout out you trip then click on the campground link.
FMCA also offers this option.
We used a book called
Next Exit. It works on the Interstate.
Pick Up a Rand McNally map from WalMart.
I used a Garmin GPS for my routes. Installed POI (points of interest) from
POI Factory in it.
There is one the almost 23,000 campsites in it. Nice feature when you are at end of day and need a campsite. Select the POI and up comes all the closest campgrounds. With phone numbers and directions. Works with other GPS's also.