How to Find Parks?

For rec.gov properties there is no better tool than these campground virtual tours https://www.campgroundviews.com/best-camping-tool-ever/

Like others have mentioned, I use Google maps. Find an area you want to go and type in 'Campgrounds" or "Rv Resorts". You may have to try a couple of different words because just typing in campgrounds may not bring up all places you can camp like some RV resorts for example and vice versa.

Dan

WOW, thanks to everybody for all the good info, this will definitely help.

This is just about my most used site, https://www.campgroundreviews.com/. Followed closely by http://www.uscampgrounds.info/.
https://www.campsitephotos.com/ is a good one, but does have limited listings.
And here are some more that I do frequent on occasions:
https://www.campgroundviews.com/?,
https://thedyrt.com/,
Of course, you mentioned, https://www.rvparky.com/,
Another decent search site is http://www.ultimatecampgrounds.com/
This is about the best site for info on a given park, but the listings are limited, https://wxtoad.com/. He does a stellar job on photos.
This is also valuable info, https://www.tripsavvy.com/state-park-entrance-passes-3362306
An amusing site is https://www.roadsideamerica.com/.
And I believe you mentioned Allstays, which has decent info to offer.
This has some interesting info but is a bit awkward to navigate., https://www.fhwa.dot.gov/byways/byways.

Allstays has been our goto because it lists nearly every park. It has a map search feature that lets you see what's in each state. It includes the COE cgs as well. It's very user friendly even on the road. You can go to the website or download the app. After trying all the others, Allstays is the one that we use exclusively now.

Go to Google and type in campgrounds. It will show a map. Click on the map and move it with your curser to an area you want to stay at. You can enter RV parks, State parks if you want to be more selective in your stays. Do the same if you only want to see whats in a certain State.
All the CG's will show up and just click on the ones you like and go to the website listed when the page pops up.

KOA.com

State Parks

Also, I'd endorse Campendium, The Dyrt, COE Parks

There's a ton of info in individual state travel guides on the internet, just surf through & see what interests you. Good luck!

You will find that combining multiple sites is better than just relying on a single site. For planning I use Good Sam and Coast to Coast and Passport America to find destinations. On the road I like RVPARKY because of the real time GPS locates where you are and identifies campgrounds nearby and on the route. I only make reservations at destinations and never for overnight stops. We start looking on RVPARKY around 2 or 3 pm for a CG on our route to be off the road by 4 or 5pm. The app gives all pertinent information to call to check availability and have one held for you. It also has filters for military campgrounds, gas stations, Cracker Barrel, Cabella's etc. It's free to download and I find it easy to use.

Welcome to the forum

As mentioned, https://campgrounds.rvlife.com is our 1st go to site. Large member/data base on reviews and useful links on the review home pages.

I will also use google reviews for comparisons.

Mike