About half the placenames in the US can be attributed to Indian sources, yeah. And then variously anglicized or corrupted to the forms we know now.
I live in Milwaukee, IIRC meaning "good waters", or a place thereof. Yet half way across the continent there's a Milwaukie. Which, I think may be more surprising in that, the root words were well enough conserved, despite the distance, despite the diversity of tribes inbetween, that they were transcribed nearly identically.
Many places here in WI, were named by early French trappers, traders, etc.; hence we have "Beloit" (in typical brutish American, "bell-oight"), from what should be more "bel-wa"; or Fond du Lac ("fonnalack"), etc. These are mixed with Indian placenames (Wausau, Oconomowoc, Minocqua, Kewaskum, etc.), and later (English and American) names of varying descriptive (e.g. Whitewater, Beaver Dam) and eponymous (Madison, etc.) origin.
Still other things weren't so lucky. "Geoduck", pronounced "gooeyduck", is a suggestively-shaped clam (also from the Pacific NW), which was even transcribed more-or-less correctly...and yet... when the written report made it back to the academic community, it was copied incorrectly, and nobody's been bold enough to, just, put their foot down and say, yes we've been spelling it "this way" for so many years but come on, the actual source material spelled it "that way" and makes far more sense and can't we just---
...But no, we can't. So we have many weird things throughout the world, because this process of transliteration, transcription, and corruption (whether written or verbal), occurs naturally.
The one upside is, this process is a source of entropy, by which we obtain specific-sounding names ("River Avon", a watercourse in England), from generic terms ("river river").
Tim