On March 13, 1997, near Phoenix, five — or maybe seven — bright lights appeared in the night sky in a “V” formation, like a strange flock of birds. Local news outlets were flooded with reports of what is now known as the Phoenix Lights, one of the more tantalizing “mass sightings” in the past few decades for those who Want To Believe. Sixty-four people reported the lights to the National UFO Reporting Center. “My wife and I were walking our dogs on the south side of South Mountain in the mountain park when we saw the ufo come over the mountain at low altitude,” one account reads. “It was s i l e n t and had 5 white globes along the leading edge of a black triangle shaped object which blacked out the stars and was about a mile wide.” But there’s another way to see the Phoenix Lights: According to a new map plotting more than 90,000 sightings from the National UFO Reporting Center’s database, it’s one of the most widely reported sightings of the past several decades. The interactive map, from Max Galka, plots each distinct sighting in the database with green and blue circles. Blue circles represent sightings reported by just one witness; green circles mean there are multiple accounts of the same event. The bigger the green circle, the more reported sightings there are of that particular event. Who knew the Chicago area was such a hotbed of UFO activity? Six of the 10 biggest UFO sightings on the map, as ranked by number of witnesses, were in Illinois, Galka noted in an analysis. The biggest was the Tinley Park Lights. UFO enthusiasts might know about them, but the Tinley Park sightings don’t even have their own Wikipedia page. The mass sighting in Phoenix is represented by that huge green dot in the southwest. In the interactive version, available here, the green dots are clickable. The map will then pull up all of the witness accounts that are available, along with any photo or video “evidence” of aliens among us. The database goes back nearly a century, Galka told The Washington Post, but the further back you go, the less complete it is. The National UFO Reporting Center started collecting first-person accounts about 20 years ago and accepts reports pertaining to any date in history. The data from recent years is much more robust, as witnesses can report what they saw shortly after it happened. For example: There are only a couple of reports of the 1947 Roswell “crash” in the database, even though it’s arguably the most famous UFO story in history. Those reports don’t show up on Galka’s map as a single event, he said, since “the dates of the Roswell reports are spaced far apart, because most are not actually ‘sightings.’ They are just events that somehow relate to the alleged crash.” A lot of the bigger sightings, according to the number of witnesses, happen in urban areas. This obviously makes sense, when discussing visible phenomenon in general: more people are around in bigger cities to see something in the sky. But when talking UFOs, that particular point tends to challenge a stereotype — that UFO sightings are the territory of rural areas of the country. “That’s true by number of reports per capita,” Galka told The Post in an interview. According to another analysis of UFO sightings, Vermont, Arizona, and Maine have the most per capita of all the U.S. states. “But it turns out that the important sightings, the ones that have some credibility behind them, are in dense areas,” Galka said. By “credible,” Galka doesn’t mean confirmed sightings of aliens. Instead, viewing America’s UFO sightings by number of witnesses, “credible” simply means that witnesses were likely responding to some actual event, which they interpreted as a UFO. “Everyone hears ‘UFO’ and they think urban legends, like bigfoot,” Galka said. “But when you have these big sightings that were seen by thousands of people, you can debate what’s up there, but that’s not urban legend, that’s just a mystery.” As the Phoenix Lights demonstrates, that mystery can linger even after a reasonable explanation. Lt. Col. Ed Jones, a pilot at the time with the Air National Guard, said that he was part of a small squadron of A-10s flying over the area that evening. The lights, he said, were flares that he and the other pilots released from their planes. Galka noticed another interesting detail that might help explain some of the other mysterious sightings: Americans have a tendency to see quite a lot more UFOs in the sky right around the Fourth of July, when towns across the country plan fireworks shows.