Highways

The interstate highway system was built not to make it easier to visit Grandma, not to make the drive to your vacation destination quicker, but for military purposes. The highways provide a way to move troops and equipment around the country in a timely way. They also can be pressed into service as landing strips for airplanes should an emergency arise.

But something else crossed my mind. What if "the walls are breached"? Then the interstate system allows for the enemy to make inroads into the country much more easily.

I remember in the Luther movie, where Cajetan was telling Luther that the Turks were at the door of Vienna and here was Luther making a silly little commotion about theology. You know, Vienna is not that far from Wittenberg! That would be (for me) like having the enemy attacking St Louis, not just New York or San Francisco. And yet, given that we are one nation and not a bunch of feudal states, and given that we do have a system whereby we can easily move around the country, there really isn't any safety in being far away from the battle-lines, is there?

So the roads that are designed to help with defense could very well make it easier for the country to be overrun too.