Keep in mind that many parks that take reservations, also keep a certain number of sites that are available for (as they call it) walk-in only. When you are on the reservation site, they will show as not available for reservation or wording just a little different that the sites you can reserve. We have traveled full-time for 8 years and have made 3 or 4 reservations in that entire time. Have only been in 1 small town where the only park was full, otherwise have always gotten a site. We aren't trying for the same parks that all the tourists flock too though. Small, in the woods, out of the way campgrounds. Many don't even have a website. Many are privately owned and inexpensive. We use rvparkreviews.com and allstays.com to find many of these places.