More than 3,000 Oregon-bound emigrants paused at the fort in 1845, intermingling peacefully with the numerous Sioux Indians encamped there. Later that summer, peace still prevailed when Col. Stephen Watts Kearny arrived with five companies of the First Dragoons, encamped on the grassy Laramie River bottoms, and held a formal council with the Indians between the two forts. Here the Indians were warned against drinking “Taos Lightning” or disturbing the emigrants and were assured of the love and solicitude of the Great White Father. They were also duly impressed with his power as symbolized in a display of howitzer fire and rockets.

While Fort Platte was abandoned by its owners in 1845, trade was brisk at Fort Laramie during the winter of 1845-46, and it is recorded that during the following spring a little fleet of Mackinaw boats, under the leadership of the veteran factor P. D. Papin, successfully navigated the Platte with 1,100 packs of buffalo robes, 110 packs of beaver, and 3 packs of bear and wolf skins. Thus, it was a moderately prosperous Fort Laramie in the waning days of the fur trade which the young historian Francis Parkman visited in the spring of 1846 and described so vividly in his book The Oregon Trail:

Fort Laramie is one of the posts established by the American Fur Company, which well-nigh monopolizes the Indian trade of this region. Prices are most extortionate: sugar, two dollars a cup; five-cent tobacco at a dollar and a half; bullets at seventy-five cents a pound. The company is exceedingly disliked in this country; it suppresses all opposition and, keeping up these enormous prices, pays its men in necessities on these terms. Here its officials rule with an absolute sway; the arm of the United States has little force, for when we were there the extreme outposts of her troops were about seven hundred miles to the eastward. The little fort is built of bricks dried in the sun, and externally is of an oblong form, with bastions of clay in the form of ordinary blockhouses at two of the corners. The walls are about fifteen feet high, and surmounted by a slender palisade. The roofs of the apartments within, which are built close against the walls, serve the purpose of banquette. Within, the fort is divided by a partition: on one side is the square area, surrounded by the storerooms, offices, and apartments of the inmates; on the other is the corral, a narrow place encompassed by the high clay walls, where at night or in the presence of dangerous Indians the horses and mules of the fort are crowded for safekeeping. The main entrance has two gates with an arched passage intervening. A little square window, high above the ground, opens laterally from an adjoining chamber into this passage; so that, when the inner gate is closed and barred, a person without may still hold communication with those within through this narrow aperture. This obviates the necessity of admitting suspicious Indians for purposes of trading into the body of the fort, for when danger is apprehended the inner gate is shut fast, and all traffic is carried on by means of the window. This precaution, though necessary at some of the company’s posts, is seldom resorted to at Fort Laramie, where, though men are frequently killed in the neighborhood, no apprehensions are felt of any general designs of hostility from the Indians.