As Richard Florida notes, while nations are based on imaginary boundaries, you can basically see mega-regions by looking at the night-side of the planet.

In other words, you can see here what Florida means by the Boston-NY-Washington mega-region. You can also pick out the sparser (less-mega?) mega-region surrounding the Great Lakes. Although the East Coast region doesn't quite reach Atlanta, I am reminded of William Gibson's BAMA (Boston-Atlanta Metropolitan Axis). From Neuromancer
Program a map to display frequency of data exchange, every thousand megabytes a single pixel on a very large screen. Manhattan and Atlanta burn solid white. Then they start to pulse. the rate of traffic threatening to overload your simulation. Your map is about to go nova. Cool it down. Up your scale. Each pixel a million megabytes. At a hundred million megabytes per second, you begin to make out certain blocks in midtown Manhanan. outlines of hundred-year-old industrial parks ringing the old core of Atlanta.