After cutting out the houses I upped the saturation and blew out the colors, then copied that layer twice. The bottom two layers I blurred, one with a wide radius and one with a tighter "glowy" radius. The I lightened the top houses to get them closer to white, and put the whole over the satellite image!
This is my favorite part of Power Grid - how an end game board looks like the country at night. And you can even see where everything lines up!
I think on the board in the city in Montana is Billings. But what my question is, doesn't it look like 5 regions are being used but there are only 4 players?? Sorry, just kidding. Its a fantastic picture!