I am from Mifflintown, and can not get much from this picture. However, courthouse research has led me to a fair ground that only operated for 20 years or so in the late 1800's. It was said to be called Riverview and on a 14 acre parcel east of Mifflintown. This would put it near the old Tuscarora Junior High School. I see on old maps that there was an old farm house on the west side of the Empire Kosher Chicken plant, along the property line heading south to the river. I believe that this land between the chicken plant, the local catholic church and the Tuscarora school was that spot.
This site is scheduled for construction of the new Mifflintown/Mifflin river bridge
If anyone can check this out the land should be in the hands of the state by this time. I have MD'd on state aquired land in similar situations, as long as no work is started, no one usually minds. It may also be that the fairgrounds and racetrack were on the lands of the school. I did not check the deeds.