I sense no patterns except fashion. Fashion is dictated by the world's elite, one's chess associates, and popular books. That can work at the club level, the state level, region level, or national level - who knows, maybe at the continent level as well. For example, certain strong players at a local club fancy the Caro-Kann as a defense to 1.e4. There is a likelihood that new impressionable players will give it a try also. But fashion is like the breeze, and can change direction very quickly. Watch Anand or Moro play an interesting and old line/opening. Pretty soon, there's an article on it, then a book. In the meantime, players in search of a new opening pick it up.

What I spoke of above refers mostly to openings. I have not seen fashion in the middle game or the endgame to any great extent (notwithstanding the fashion of putting a knight on the rim occasionally because Deep Blue or Deep Thought or Deep Rybka or Deep (fill-in-the-blanks) played it in a seminal match versus some human schmuck.

Specifically what do you see...from those pesky Americans

Our local club closed a year or so ago, and I no longer play in OTB events on a regional level. Thus, I have no current information on what's going on. A review of games in Chess Life would be a place to look. But perhaps better would be games from the National Open or other large event. However, only games from the top section would likely be available from such an event - and that wouldn't tell us much about fashion at the club level. Another idea would be to search out club-strength players here at chess.com, perhaps those who can be identified as claiming to hale from a particular geographical area. Then examine the opening choices. Of course, undertaking such an activity would have to be a labor of love - it would be a LOT of work, with no clearly discernible outcome as a definite possibility.

Opening the perambulaters further,how about this one.................................

" CHESS MATHAMATICAL DIALECT/WORLDWIDE REGIONAL ACCENT, ON THE BOARD".