I have not stayed here yet but have researched this location for future use, and want to share what I have learned as there are few RV parks in the Decatur area. The RV sites are located outside the northeast corner of the racetrack. 30 amp electric hookups and water faucets are grouped together. If you were here during an event you would likely need a long water hose and shore power extension cord. I have not found a dump station on the grounds but was told by a caretaker that they have provisions for emptying holding tanks, but he did not elaborate. This is not the type of RV park where you can just show up any time and get a site. It is best to call the fairgrounds office a day in advance and arrange your arrival date, length of stay, etc. The fairgrounds are located near the edge of town, and I hate to say it but Decatur has been in decline for a while. The fairgrounds could be a quite place at night, but I would be a little concerned about security. Fairgrounds staff would be able to better advise you on that at the time of your stay.
They do NOT rent sites UNLESS there is an event...no exceptions