>>>couplings of three cities elsewhere share the same name<<<

In Tennessee, near where my parents live there is an area called Tri-Cities. It includes Bristol, Johnson City, and Kingsport.

In North Carolina I know of no "Tri-Cities," but there are the Triad and the Triangle, which are both groupings of 3 cities. I live in the Triangle, which consists of Raleigh, Durham, and Chapel Hill. The area inside the 'triangle' is called Research Triangle Park. (lots of high tech universities in the triangle, and lots of high tech companies in RTP)