The creepy clown ebb and flow is currently in full flow, so Atlas Obscura has created the definitive creepy clown incident map, replete with dates, details, and outcome.
They trace the recent rash to August, when multiple witnesses saw creepy clowns, sometimes wielding green lasers, in Greenville, South Carolina:
And with that, clown hysteria began. Next came clown sightings in nearby North Carolina. And, then, sightings—and, increasingly, social media threats—up and down the Eastern Seaboard. By mid-September, the sightings and threats had moved west, to Middle America. And by late September and early October, they'd reached the West Coast.