It's gone through various incarnations and sponsors, but the annual bike race here in the urban hellhole has been a tradition for quite some time. It isn't just a bike race, but a street/park party, too. In other words, it's one of those days when the cops pretend public drinking is legal.
Overall the city isn't too bad with such things. Block parties are pretty easy to organize, and there are lots of street festivals and popup venues these days. But these things are usually incredibly popular and crowded. That's mostly a good thing, but it points to the fact that for whatever reason people like to drink in public places and there is a tremendous shortage of times/places when they are allowed to do that.
Urban hellholes have a comparative (and absolute) advantage in public spaces. They should exploit that more. Either that or build another wing onto the convention center.