"For those interested in exploring the actual movements of people and objects, however, maps representing illegal flows tend to suffer from a surfeit of arrows or “arrow disease.”
Arrows are especially unhelpful in the case of borders. A recourse to arrows feeds on a misconception: that illegal flows cross borders without affecting them or being affected by them. As long as we see borders primarily from the perspective of the territorial state, as its outer skin that needs to be protected from penetration by unwanted aliens and outlawed substances, we will tend to fall prey to arrow disease and the underlying idea that borders and flows are antonyms."
Willem van Schendel, “Spaces of Engagement: How Borderlands, Illegal Flows, and Territorial States Interlock” in Illicit Flows and Criminal Things: States, Borders and the Other Side of Globalization. Willem van Schendel and Itty Abraham (eds.) Pg. 43. Indiana UP 2005.