Yes, I can imagine some branches in America. Some centuries ago it was always the oldest son inheriting the fortune and title of being the head of the family. The younger brothers mostly had to look elsewhere for making a name. I think that could have happened in the wizarding world as well.

Or if you have a son who wants to have adventures, he might have moved to the colonies as well, to help explore the vast unknown territories the American continent offered.

A third reason to move to the Americas might have been that they were outcasts. We know the Blacks erased sons and daughters from their family tree when they married Muggles or Muggle-borns or did something else which stood against the family beliefs. The colonies would mean a relatively safe place for the outcasts to move to. There no one knew their background and they could start anew.

/my three Knuts

Hope to have helped,