How long can a river be?

Answer:
From its source to its mouth.
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If you didn't find that helpful, which most of you should not, the longest river is the Nile which is 6,000 meters long and can get as small 500 meters, so i hoped that helped. :)
First answer by Williammtrent. Last edit by Briar is cool. Contributor trust: 0 [recommend contributor recommended]. Question popularity: 1 [recommend question].