Rivers High‑importance

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Geology Mid‑importance

	Geology portal Talk:Main stem is part of WikiProject Geology, an attempt at creating a standardized, informative, comprehensive and easy-to-use geology resource. If you would like to participate, you can choose to edit this article, or visit the project page for more information.GeologyWikipedia:WikiProject GeologyTemplate:WikiProject GeologyGeology articles
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Added to the definition

I added this to the definition: "The mainstem extends all the way from one specific headwater to the outlet of the river, although there are multiple ways to determine which headwater (or first-order tributary) is the source of the mainstem." Then I added a "Clarification needed" tag.

I added this to emphasize that the mainstem is not just the segment of the river with the highest order (near the outlet), it stretches all the way to one specific first-order tributary that must be chosen by some method.

Unfortunately, I can't find a concise and specific definition. The USGS provides maps of many river mainstems, each with one special headwater chosen as the "source", but they don't say how the source is chosen. Some other sources claim the mainstem is whatever river path is the longest distance from headwater to outlet, but simply looking at the Mississippi according to the USGS seems to indicate they are using a different definition. I found no sources that explained the USGS data, and they have lots of data on headwaters, tributaries, and mainstems. So I left it completely uncited. 209.6.225.254 (talk) 07:04, 17 January 2024 (UTC)[reply]