Minnehaha is from the Dakota Mníȟaȟa — mní (water) + haȟa (waterfall, laughing) — waterfall or laughing water. The poem's meter (trochaic tetrameter) was modeled on the Finnish Kalevala. The Minnehaha Falls in Minneapolis, Minnesota is named for the heroine. 9 From the New World (1893, Largo movement).
Minnehaha does not currently appear in the US Social Security Administration's top 1,000 girls' names, so we don't publish a US rank or birth count for it. That says nothing about the name's standing elsewhere in the world — only that it sits outside the ranked US data we rely on.
—
In Pythagorean numerology the letters of Minnehaha reduce to 1, The Leader. This is a traditional interpretive system, not a factual claim about the name.