UPPSC 2023 Prelims GS Paper-I · Question 97 of 150

Correct — D, The Rio Grande. The Rio Grande (called Rio Bravo in Mexico) forms a large part of the international boundary between the United States and Mexico, running from around El Paso/Ciudad Juarez down to the Gulf of Mexico and marking the entire Texas-Mexico border. So the border river is the Rio Grande.

• (a)The Colorado — The Colorado flows through the south-western USA and into Mexico near its mouth, but it does not run along the US-Mexico border as a boundary river the way the Rio Grande does.
• (b)The Mississippi — The Mississippi is a major internal US river draining the central plains into the Gulf of Mexico; it lies wholly within the United States and touches no international border.
• (c)The Amazon — The Amazon is in South America (mainly Brazil, Peru, Colombia) — a different continent altogether, nowhere near the US-Mexico frontier.

Rivers often serve as international boundaries. The Rio Grande / Rio Bravo is the classic North American example: since the 1848 Treaty of Guadalupe Hidalgo it has defined the boundary between Texas (USA) and Mexico, flowing roughly 3,000 km from Colorado to the Gulf of Mexico.

The distractors are all famous rivers, so the trick is knowing which one is actually a boundary. Colorado and Mississippi are US rivers but not the border; the Amazon is on another continent. Only the Rio Grande fits 'along the US-Mexico border'.

• Rio Grande (Rio Bravo del Norte in Mexico) marks the entire Texas-Mexico border.
• It became the boundary after the 1848 Treaty of Guadalupe Hidalgo ending the Mexican-American War.
• It rises in the Rocky Mountains (Colorado) and empties into the Gulf of Mexico.
• The Amazon (South America), Mississippi and Colorado (both USA) are not US-Mexico boundary rivers.

• Picking the Colorado — it enters Mexico but is not the border river
• Confusing the Amazon (South America) with a North American river

UPSC/UPPSC ask which river/lake forms the boundary between two named countries, or to match a river to its country.

• practice — not a real PYQ

  The Rio Grande forms the international boundary between the United States and which country?

  • (a)Canada
  • (b)Mexico
  • (c)Cuba
  • (d)Guatemala

  Answer(b) Mexico — the Rio Grande marks the Texas-Mexico border.

• practice — not a real PYQ

  Which river drains the central United States and empties into the Gulf of Mexico without touching any international border?

  • (a)Rio Grande
  • (b)Colorado
  • (c)Mississippi
  • (d)Columbia

  Answer(c) Mississippi — a major internal US river.