<i>Colorado. "Round up" on the Cimarron</i>, a <a href="https://en.wikipedia.org/wiki/photochrom" class="extiw" title="en:photochrom">photochrom</a> print from c. 1898, showing one of the large musters of cattle done in the days before barbed wire, fences, and easy access to transport ended the necessity for the practice.
<p>This is almost certainly in the town of <a href="https://en.wikipedia.org/wiki/Cimarron,_Colorado" class="extiw" title="en:Cimarron, Colorado">Cimarron</a>, compare the 1883 photograph on the right. 
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&lt;The LoC identify the river on the left as being the Cimarron River. There are several rivers of that name in the Colorado area, but given the very easily-identifiable mountain in this image, this would be the <a href="https://en.wikipedia.org/wiki/Cimarron_River_(Gunnison_River)" class="extiw" title="w:Cimarron River (Gunnison River)">one that is the tributary of the Gunnison River</a>.
William Henry Jackson (April 4, 1843 – June 30, 1942); Detroit Photographic Co.
"Copyright 1898"
<a rel="nofollow" class="external text" href="https://www.loc.gov/pictures/item/2008678198/">Library of Congress</a>