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What would make a river the world's shortest?

Calling a river the world’s shortest sounds like a measurement problem, but the rules come first. What qualifies as a river, where does it begin and end, and at what water level is it measured? Montana’s park authority describes the Roe River as a former record holder. That offers a real case without settling every competing claim.

3–7 min

Questions you could explore

  • How could changing the source or mouth boundary change a ranking even if nobody measured carelessly?
  • What evidence would be needed to compare two claims made under different rules?

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