A neighbourhood street party, closing off a section of road for an afternoon of shared food and casual conversation, might look like pure celebration, but it also functions as a form of quiet social infrastructure, giving residents who live close together but rarely interact a low-pressure reason to actually meet.
The informality is part of what makes it work: no formal agenda, no particular obligation beyond simply showing up, which lowers the barrier to participation for residents who might feel too busy or too unsure for anything more structured or demanding of their time and attention.
The relationships formed at one afternoon gathering tend to outlast the event itself, since a face recognised from the street party becomes a face worth greeting afterward, which is often exactly the kind of small, cumulative familiarity that makes a street start to feel like a genuine community. What makes the difference, in practice, is rarely a single decision but a long run of small ones.