I use the internet to google a certain area or community to find campgrounds. Often I'll put in the city or county name and do a search. And yes, often just stumbling on them, but that's another gem in this big wonderful country.
Melissa, in the Walmart Atlas the county names are written in a gold color. If you look at Brunswick, GA you'll see GLYNNin gold just above and if you look closer you can see the county outlined with a gold broken line.
Joy A. & Lily
and "Puff", too
No. Ca. Sierra Foothills