structural:summarization
American exploration

In the 1820s, American fur trappers along the upper Green River in Wyoming (known to them as the "Seedskeedee" or variants thereof), seeking a route to export furs to the coast, surmised that this and what the Spanish called the Colorado were in fact connected. William H. Ashley made an unsuccessful attempt to navigate from the Green River to the Colorado's mouth in 1825. In 1826, Jedediah Smith arrived at the lower Colorado River, referring to it as the Seedskeedee, and proceeded upstream, exploring as far as Black Canyon. During the 1830s, various fur trappers from Wyoming made it as far downstream as Cataract Canyon and Glen Canyon, but none were able to navigate the full length of the river. In 1843 John C. Frémont explored the Great Basin and conclusively determined no Buenaventura River flowed west to California; thus, the direction of river flow must be southwest.

By the early 19th century, the stretch of the Colorado above the confluence of the Green River at Cataract Canyon, Utah, became known to fur trappers as the "Grand River", though the exact origin of this name is unknown. The Grand River above the confluence with the Gunnison River was also called the Bunkara River, the Blue River, or the North Fork of the Grand River until the 1870s. By the early 1900s the name "Grand River" had been attached to the entire stream as far as Grand Lake, which was then considered its official source. Although the Grand River was renamed the Colorado in 1921, its name survives in numerous places such as Grand County and Grand Junction, Colorado.

In 1848 the U.S. Army established Fort Yuma, creating the first permanent U.S. settlement along the river. This served as a military garrison and supply point for settlers headed to California along the Southern Emigrant Trail. Due to the arduous task of ferrying supplies overland, the schooner Invincible attempted to bring supplies up the river but was thwarted by the delta’s strong tides. Steamboats were brought to the river, starting in 1852 with the sidewheeler Uncle Sam, whose first voyage from the Gulf to Yuma took fifteen days. Exploration by steamboat soon advanced upriver. In 1857, George A. Johnson in the General Jesup was able to reach Pyramid Canyon, over 300 miles (480 km) north of Fort Yuma. He was followed by Lt. Joseph Christmas Ives who used a specially built shallow-draft steamboat, Explorer, to reach Black Canyon, where Hoover Dam stands today. Having set out to determine the river's suitability as a navigation route, Ives remarked: "Ours has been the first, and will doubtless be the last, party of whites to visit this profitless locality. It seems intended by nature that the Colorado River, along the greater portion of its lonely and majestic way, shall be forever unvisited and undisturbed."

The last part of the Colorado River to be surveyed was the Grand Canyon itself. In 1869, John Wesley Powell with nine men set out on an expedition from Green River Station, Wyoming. They were the first part of non-natives to travel the length of the Grand Canyon, and the first to successfully travel by boat from the upper Green River to the lower Colorado. Powell led a second expedition in 1871, with financial backing from the U.S. government, and continued to conduct geographical and botanical surveys across the region until the 1890s. Another Grand Canyon river expedition was led in 1889-1890 by Robert Brewster Stanton to survey a route for a proposed railroad through the canyon, which was never built.

We are now ready to start on our way down the Great Unknown. Our boats, tied to a common stake, are chafing each other, as they are tossed by the fretful river. They ride high and buoyant, for their loads are lighter than we could desire. We have but a month's rations remaining… The lighting of the boats has this advantage: they will ride the waves better, and we shall have little to carry when we make a portage.

We are three-quarters of a mile in the depths of the earth, and the great river shrinks into insignificance, as it dashes its angry waves against the walls and cliffs, that rise to the world above; they are but puny ripples, and we but pigmies, running up and down the sands, or lost among the boulders.

We have an unknown distance yet to run; an unknown river yet to explore. What falls there are, we know not; what rocks beset the channel, we know not; what walls rise over the river, we know not; Ah, well! we may conjecture many things. The men talk as cheerfully as ever; jests are bandied about freely this morning; but to me the cheer is somber and the jests are ghastly.