Our next stop is the border between Afghanistan...

Our next stop is the border between Afghanistan and Pakistan. Known as the Durand Line, this mountainous frontier is difficult to monitor because of its rugged terrain. Security concerns and cross-border tensions have made it one of the most closely watched borders in the region. Now let's travel to the border between the United States and Mexico. Spanning deserts, rivers, and cities, it's one of the busiest international borders in the world. Millions of legal crossings happen every year, while both countries also work to address challenges such as illegal trafficking and unauthorized crossings. Finally, we arrive at the border between Russia and Ukraine. In recent years, this border has become one of the world's most closely followed frontiers because of ongoing conflict, leading to significant humanitarian and security concerns. These borders remind us that the lines separating nations are shaped by history, geography, and politics—not just maps. Which border surprised you the most? Let us know in the comments, and subscribe to World Decoded for more fascinating stories from around the world.