opean continent, where _depots_ could be
established along the line of march. To appreciate such preparations, it
is necessary to understand the character of the country to be traversed
between the Missouri River and the Great Salt Lake.

The route selected for the march was along the emigrant road across
the Plains, first defined fifty years ago by trappers and _voyageurs_
following the trail by which the buffalo crossed the mountains,
described by Lieutenant-Colonel Fremont, in the reports of his earlier
explorations, and subsequently adopted by all the overland emigration
across the continent. It is, perhaps, the most remarkable natural road
in the world. The hand of man could hardly add an improvement to the
highway along which, from the Missouri to the Great Basin, Nature has
presented not a single obstacle to the progress of the heaviest loaded
teams. From the frontier, at Fort Leavenworth, it sweeps over a broad
rolling prairie to the Platte, a river shallow, but of great width,
whose course is as straight as an arrow. Pursuing the river-bottom more
than three hundred miles, to the Black Hills, steep mounds dotted with
dark pines and cedars, it enters the broad belt of mountainous country
which terminates in the rim of the Basin. Following thence the North
Fork of the Platte, and its tributary, the Sweetwater,--so named by an
old French trapper, who had the misfortune to upset a load of sugar into
the stream,--it emerges from the Black Hills into scenery of a different
character. On the northern bank of the Sweetwater are the Rattlesnake
Mountains, huge excrescences of rock, blistering out of an arid plain;
on the southern bank, the hills which bear the name of the river, and
are only exaggerations of the bluffs along the Platte. The dividing
ridge between the waters of the Atlantic and Pacific is reached in the
South Pass, at the foot of a spur of the Wind River range, a group of
gigantic mountains, whose peaks reach three thousand feet above the line
of perpetual snow. There the emigrant strikes his tent in the morning
on the banks of a rivulet which finds its way, through the Platte,
Missouri, and Mississippi, into the Gulf of Mexico,--and pitches it, at
his next camp, upon a little creek which trickles into Green River, and
at last, through the Colorado, into the Gulf of California. Not far
distant spring the fountains of the Columbia. A level table-land extends
to the fords of Green River, a clear and rapid s