There are two other graphic maps at the Slate site
By Angela Tchou
In the past 15 years, the Davenport, Wash.-based National UFO Reporting Center has collected more than 30,000 reports of UFO sightings through its hotline and Web site. The following three maps visualize that rich history.
The first plots every sighting as a small yellow dot, with lighter colors representing a higher density of reports.