It's in early August, and now over. I have gone a number of times over many years. I camp in a biker campground west of Sturgis in Belle Fourche, South Dakota (pronounced Bell Foosch).
It was once very crazy & lawless, mostly Harley biker bums and their bitches. Killings were common, nudity & sex right out on the street. Sturgis is a very small prairie town in the middle of nowhere, west of Rapid City where Mount Rushmore monument is located, close to the Black Hills.
Before World War II Sturgis was the site of local dirt flat-track motorcycle races, and hill climbs, sponsored by the Jackpine Gypies motorcycle club. The Gypsies still hold the rights to the current Sturgis rally, though now managed by an events corporation.
It is unclear what attracted the attention of motorcycle clubs and gangs to Sturgis, especially beginning in the 1960s. At that time only difficult local roads led there, before US Interstate 90 came through. After I-90, the Sturgis rally boomed.
It became crazy in the 1970s and '80s, and the town, county & state decided to control the rally. It's often called a Harley rally, but that's not strictly true, just that most of the bikers ride on them. It's also the biggest tourist money raiser for the entire state of South Dakota, even exceeding Mount Rushmore.
By the early '90s the town and the Jackpine Gypsies club contracted with an events corporation to run the thing. I think they're now on their second company, which has security police everywhere, and they charge fees for the roughly 1000 vendors who now show up. The knifings & nudity are now much reduced.
Indeed, it's become something of a Mom & Pop Winnebago event, with motorcycles trailered there behind motor homes & pickups. Vendors sell lapel pins & patches that read "I Rode MIne!" for those bikers who actually ride their bikes the whole way, as I do. In fact, one year I rode my bike from South Florida, the longest distance you can ride in the lower 48.
Attendance for the 10 days usually exceeds 500,000. I just go into Sturgis itself for 1 day, to walk the packed sidewalks, and buy that year's souvenirs. The rest of my several day stay I spend riding the Black Hills and seeing the local sights.
Downtown Sturgis is too crowded & dangerous, with thousands of novice bikers crashing into each other. Plus it can also be incredibly hot in early August, the temps sometimes exceeding 100 degrees F. You don't wanna be sitting on jammed streets under the searing August sun going nowhere.
And that is Sturgis.