Think about that for a moment.  Certainly fits with what most city downtowns are like — swarms of both tourists (rare visitors) and the people who work (or live) there.  Empirically the number of visitors scales inversely as the square of both the distance traveled and the frequency of visitation.  But geography is two-dimensional while time is one-dimensional, and the world is a big place with lots of people who travel.  So you end up with a lot of people from far away who don’t visit that often, and the folks who live there.  But not many people from middle distances, who visit often.

To learn more about the math and data behind that statement, read the blog post by Robin Hanson about Geoffrey West’s new book, Scale:  The Universal Laws of Growth, Innovation, Sustainability, and the Pace of Life in Organisms, Cities, Economies, and Companies (link from Robin Hanson’s post).