The longest border between any two countries in the world is between:
Answer & explanation
Answer: (a) Canada and the United States of America
Canada and the United States share the longest international border in the world, about 8,891 km (5,525 miles) as maintained by the International Boundary Commission. Every other pair listed, including Chile-Argentina, China-India and Kazakhstan-Russia, has a shorter border.
- ✓ (a) The Government of Canada describes the Canada-US land border, at close to 9,000 km, as the longest international border in the world. The joint International Boundary Commission gives its length as 8,891 km.
- ✗ (d) Kazakhstan and Russia share a very long land border, but it is shorter than the Canada-US boundary.
- ✗ (b) The Chile-Argentina border is long and runs along the Andes, but it too is shorter than the Canada-US boundary.
Remember · World's longest international border: Canada-United States, about 8,891 km (5,525 miles).
Sources
- Global Affairs Canada, Canada-United States relations ↗ · reference work “Canada and the U.S. share a land border that, at close to 9,000 km, is the longest international border in the world”
- International Boundary Commission (Canada and the United States), The Boundary ↗ · reference work “the line snakes 8,891 kilometres or 5,525 miles across North America”
Question and answer: UPSC's official GS Paper I (2024, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). ·