Unusual vapor trail observation in Cheyenne Wyoming

Summary

A civilian witness in Cheyenne, Wyoming, reported unusual vapor trails on July 16, 1957. The first trail appeared as a very faint and narrow arc, forming a 180-degree curve in about 12 seconds. No aircraft or object was visible ahead of the trail. As it developed, perpendicular crosses formed progressively, wider than the trail itself. A second straight trail moving west to east appeared about half a minute later. Both trails disappeared within five minutes. Investigators concluded it was likely an aircraft at high altitude, where contrails are often visible without seeing the plane.

The explanation given was that the trails were typical contrails from high-flying aircraft, and the unusual pattern was a normal atmospheric effect. No photographs or radar data were involved, and the witness was a civilian. Despite the strange appearance, there were no unexplained elements in the report.