So, How big was a family?
--Rich Parsons
It was the basic family unit (mother, father, kids, grandparents, etc). But most of the families within a baranggay would be related in some way.
A baranggay is essentally a neighborhood or subdivision, or even a "quarter" of a town or city.
Modern Filipino Baranggays are distinct political units outlined in the Constitution of 1987. Those are kind of what Tim is talking about. The baranggay has a captain similar to an alderman.
Modern Filipino government is arranged like this:
Country >> Province >> Municipality >> Baranggay
example: Zambales >> Botolan >> Baranggay Batonlapoc
or
Country >> Chartered City >> Baranggay
example: Mandaluyong City >> Baranggay Malamig
Before 1973 all Baranggays were called "Barrios". During the Marcos Era, the Barrio was changed to Baranggay when Tagalog had many other words and structures added to it and became officially called "Pilipino". That period was a time of movement toward revitalized cultural awareness and elimination of the symbols of a colonial past.
It's really important to remember that the current Baranggay is different than the Baranggay of the past, although it did emerge from it. People might say "Baranggay Chief" but they in no way mean
chieftain or Datu just like when they say "Baranggay Captain" they don't mean that he commands a boat or is a naval officer of any sort.
Datu invokes a feeling that calls out of a distant past.
This government structure I've laid out is just the large parts. Here in the US it goes roughly Country >> State >> County >> City >> District. There are many other smaller layers that make up any of the big layers. Civics is complicated wherever you go, but the Philippines doesn't allow as much local control of governmental infrastructure as the US does, so the differences in the non-autonomous regions are very little when it comes to governmental structure at the local level comparatively.