My father and I (age 25) were coming home from late-night fishing on a pier at Tunica, MS. The road was very straight in that place. On the way home we saw a large glowing oval in the distance low to the horizon down the road from us. It hovered there over the road as we got closer and closer. At first I thought it was a blimp with lights shining onto it. It was oval and glowed white like a fluorescent light. No surface details were visible. We got closer and closer to it. When we got about 500 to 1000 feet from it we saw that it was hovering above a highway clover-leaf that was being constructed. It appeared to be about 70 feet wide and 25 feet thick...and oval...much like a blimp. We stopped...rolled down the windows and heard no sound...saw no surface details. It suddenly disappeared over the horizon in a little over a second without making any sound. I was astonished at its speed and instant acceleration. At this time I was a college graduate (Memphis State Univ)with emphasis in biology and chemistry. Later I called the Memphis airport to ask if they saw something unusual on their radar at the time of our sighting. They said no. It never seemed to be more than about 200 feet above the ground.