I was driving South on Hwy DD approaching stop sign at Hwy D, on the West end of the Busch Wildlife Area.
Just past the intersection, estimated ½ mile from me, the craft appeared in the darkness when a blueish corona or ionized gas cloud appeared at the back end of the craft.
The blue corona effect lasted for 3 to 4 seconds. During this time, the light from the corona illuminated the side of the craft forward from the rear, until the sides curved out of the line of the light source, so I was able to see the craft for some distance forward of the back end.
The back end was a flat oval shape, and the bottom appeared flat. I estimate that it was 60' to 100' across at the back.
The craft was moving very slowly to the West, or to my right.
2 nights after my sighting, the following Sunday, there were TV news reports of the sightings in Illinois on the East side of St Louis the previous Wednesday. Prior to those reports, I was not aware of the Illinois sightings which occurred 2 days before my sighting West of St Louis.
There were obvious differences between my sighting and the Illinois sightings.
In Illinois they reported lights shining to the ground, like searchlights or running lights, which were not evident in my sighting.
They reported a craft that was triangular in shape, whereas in my sighting the craft appeared to have sides that curved from the back to the front, as if the craft was shaped like a long oval with a flat back end.
Although I could not see all the way to the front of the craft.