This is a guest post by Lisa Grove. For over two years I went to the same Dunkin’ Donuts every morning outside of the subway station across the street from my office building in Midtown Manhattan. I was always there during the same hour of the day as the flood of commuters from the E and M trains stopped to get their coffee, breakfast sandwich, or donut, before heading into work, and I typically saw familiar faces in line with me each morning. Even in a city populated by millions of people, patterns of overall behavior, like those in the line at my Dunkin’, aren’t hard to find.