Geography
Why Do National Borders Cause Trade Barriers and Conflicts?
Quick fact
The world's busiest land border crossing (San Ysidro, US-Mexico) sees over 100,000 vehicles per day, yet the same border also creates the largest bilateral trade relationship in the world, while simultaneously being a source of intense political conflict over immigration and tariffs.
Why this is interesting
You can buy the same phone in two neighboring countries, but one costs significantly more. Why? The invisible line on the map—the national border—is the culprit.