A new mapping of UFO sightings from across the country makes clear that Northern Illinois and the Chicago area specifically is a hotbed of...well, something. No one knows for sure, of course, what might be causing the reports.

The map is pretty amazing. It represents more than 90,000 reports of paranormal activity in the United States dating back to 1905. Each dot is complete with date, shape, and number of witness reports.

You'll notice smack dab over Northern Illinois and Chicago is a huge patch of green circles. What does it mean?

Six of the 10 most widely spotted UFO events have hailed from Illinois, according to Galka. These include the Tinley Park Lights, a mysterious procession of three glowing objects in 2004 that “maintained a steady pace similar in speed to a dirigible,” according to a witness. (They might’ve been the same Asian sky lanterns people set loose over San Francisco.) There’s the reappearance of the Tinley lights in 2005 as a “frigging massive” structure “as big as the Tweeter Center,” claims one dude, and also a red-hued flotilla in 2001 that an observer likened to “ancient language/symbols.”

The mapmaker speculates it might be due to O'Hare Airport being a huge hub for air traffic. However, the appear to be no other examples of so many reports near other large airports.

Rockford is represented by a handful of incidents, including one from January 10, 2001 that had 25 reported witnesses.