The Border Is a Network Problem
I crossed the border between China and Korea fourteen times. Each crossing required a different route, a different assessment of patrol patterns, a different calculation of risk. The border was not a line. It was a problem, and the problem had solutions, but each solution was temporary, and the cost of getting it wrong was death.
I describe this not because the details of 19th-century border crossing are directly applicable to the present. I describe it because the structure of the problem has not changed. What has changed is the terrain.