app or site

Yes, try RVParky

WoodGlue

I kind of like this site. You can just click on the state you are interested in as a map and it will provide you with the sights in the state and you can click on an individual site.

Allstays campgrounds

Not sure if this is what you have in mind but thought it might work for you.

goggle maps will so you the rv parks

I get a ton of use out of www.rvparkreviews.com. They have a radius search feature (not sure it goes up to 400 miles though) that lists reviewed camping. I've found many great spots this way and it makes travel planning much easier. It is my go-to spot when doing initial travel planning. It is not perfect - there are many great campgrounds that have not been reviewed in their database yet... but it is pretty good.

http://corpslakes.usace.army.mil/visitors/

A great source for public campgrounds is The Ultimate US Public Campgrounds Project.

Ted H.

The Allstays Camp & RV Parks Campgrounds app is all I use now to plan travelling.

http://www.allstays.com/apps/camprv.htm

http://www.rv-clubs.us/rv_campgrounds.html

Rend Lake is in southern ILL and has 5 campgrounds and it's one of my favorites places to go in IL also Ill has some good SP's

This is exactly what you are looking for =

http://www.epgsoft.com/CampgroundMap/

Put in the location you want to start in, zoom in to see all of the campgrounds with links to the RVPark Reviews site. Zoom out to the radius you want to check on for campgrounds and you will see what there is.

I start planning all of my trips with this website. Put your mouse pointer over the campground symbols to get the details and links.