I made a reservation in January for Ridgeway State Park Colorado in July. I wanted to be in a specific park during a specific time of the month camping close to the river. The entire Ridgeway campground complex has probably close to 300+ campsites, but about 10 that I consider prime real estate.
New Mexico & Colorado are the closest mountains to Texas where you will be able to cool off during the summer. There will always be a campsite available somewhere, though it may be less than ideal. If it were just me and my wife, we might be a little bit more carefree, but traveling with three boys, it helps to plan ahead a little.
