My wife and I are in the process of planning our trip across the US this summer. We plan to be gone for 5 to 5 1/2 months ,leaving Florida in mid May and traveling north through probably Missouri then taking westerly route probably through South Dakota and Wyoming on to the Oregon , Washington area. Coming back we would take a route through Northern California .Arizona , New Mexico and then Through Texas. My main question , how long before hand must we make reservations to get campsites close to the national parks. We would like to just take it kind of one week at a time so if we are in a place where we want to stay extra days we can.We know there is a lot to see and if we make reservations too far ahead we are afraid we will have to leave some places before we may want to. We would like to know what other people's experience has been with getting campsites close to the national parks with out making reservations a long time in advance. Bye the way we will be a 38' Class a motor home. We are members of Passport America and Good Sam's as well having access to military Fam Camps as my wife is retired civil service so we have a fairly good range of parks to try and find sites if they are available. Thanks ... Alan