We find the approximate area we want to stop and then on google maps search box indicate "campground or rv parks near _____" They will show up on the map, click and many will have a connection to the parks website. Some smaller parks will not have one so there is limited information. State parks are not included, but you can easily see symbols for the state parks on the map. We also use passport america locate a campground and good sam's site. A general internet search will turn up other, and then allstays. I look at multiple sources to narrow down which campgrounds we want to consider. We have never made a reservation in 3 years of full timing.