(Lucius Quintius Cincinnatus) Lamar,[3] then Secretary of the Interior (March 1885 – January 1888), and a former slaveholder and author of the Mississippi Ordinance of Secession.

[4] Osborne Russell in his 1921 Journal of a Trapper described the Lamar as follows: Chapter-VI-In the Yellowstone Country-A Garden of Eden Inhabited By a Small Party of Snake Indians - On the 28th [July 1834] we crossed the mountain in a westerly direction through the thick pines and fallen timber, about twelve miles, and encamped in a small prairie about a mile in circumference.

The stream, after running through the center in a northwesterly direction, rushed down a tremendous canyon of basaltic rock apparently just wide enough to admit its waters.

Here we found a few Snake Indians comprising six men, seven women and eight or ten children, who were the only inhabitants of the lonely and secluded spot.In 1869, the Cook–Folsom–Peterson Expedition encountered the Lamar River (East Fork) just upstream from the canyon section flowing into the Yellowstone and traveled upstream to the confluence of Calfee Creek where they camped on September 16, 1869.

Cutthroat trout in the Lamar offer good dry fly fishing with heavy hatches of caddis, pale morning duns, and large Green Drakes in July.

[9][10] The Lamar and its tributaries are not usually fishable until about the second week of July, because of high water, so check conditions by contacting local fly stores.

However, campsite 3L2 can be hard to access in the spring when the Lamar River is high, as it requires a ford in order to reach it.

Along the upper sections of the trail one can find outfitters offering guided trips on horseback to go deep into the wilderness.