Reservations can be made at Recreation.gov. Sites in the park go on reservation on 5/15 till Oct? This is a SITE SPECIFIC SYSTEM. You may have it unless someone else has booked it for later on, then you'll have to move. You are better off checking and making a reservation after that time. Till 5/15 it is first come, first serve! This weekend Elkmont filled up, the first loop and one of the two across the river. The K-M"s? will not open till 5/15, I asked. I have a site reserved in it for Troutfest Weekend and was coming down to fish the week before. I'll have to set up else where then move on Friday(:<).