Every August, for ten days centred on the second week of the month, Sturgis becomes one of the most densely packed places in North America. The Sturgis Motorcycle Rally has run since 1938 and now draws somewhere between 400,000 and 700,000 riders and spectators — the exact figure is contested, but the effect on the town is not. Main Street becomes a slow parade of custom bikes; concerts run every night at multiple venues; vendors fill every available lot selling leather, chrome, and everything motorcycle-adjacent.
If bikes are your thing, this is a pilgrimage. If they're not, come in July or September: the Black Hills are just as beautiful and the hotels cost a fraction of rally week prices. The rally is centred on Main Street and the Sturgis Rally Grounds, but satellite events spread across the entire Black Hills region.