There was only one known vampire settlement where all the thirteen families lived together. They were condensed to one area because this was where all the resources were and where all the leaders were gathered. Similar to a human city. It made it easier for family leaders in a way to keep an eye on them and control them.
If one was to leave the settlement, they could only do so under strict rules, this was all because the vampires wish to keep themselves a secret.
On the surface, and to the people it would appear as if they were one unit working together. However, those higher up knew there was more of a divide than others thought between the thirteen families.
Even in the past, the special fourteenth family and split off and made their own settlement, something many vampires didn't know about today.