I don't know if it's illegal or not in Detroit now, but certainly everyone in my neighborhood used to drink beer on the porch and even in the yard quite openly when I was younger. In those days everyone brought coolers and drank beer at barbecues and at the beach on Belle Isle too. Certainly I had more than a few Strohs while sitting out on my nice shady front porch back in the 70s and 80s.

It is definitely illegal in NYC to drink outdoors anywhere that isn't specifically licensed for it. You can and will get ticketed for it [[and it's a damned expensive ticket), or even arrested, and certainly will be if you're doing it in a park. Keep in mind that most people in NYC don't have porches, and don't live in their own homes but in rental apartments, so parks are pretty heavily used. This law wasn't enforced much for a long time, but since Giuliani came into office it has been. The dark side of "broken window" theory policing [[and the cash that can be raised by it) is just this kind of petty harassment of otherwise pretty innocuous activity.