ile it took them from 1608 to 1659 and
1662 to penetrate upstream from Quebec to this central watershed, only
nine years elapsed from the time (1673) Marquette reached the westward
flowing Wisconsin River to 1682, when La Salle reached the mouth of the
Mississippi.

[Sidenote: Effect of current upon trade and expansion.]

The effect of mere current upon the course of trade and political
expansion was conspicuous in the early history of the Mississippi
Valley, before steam navigation began to modify the geographic
influence of a river's flow. The wide forest-grown barrier of the
Appalachian Mountains placed the western pioneers under the geographic
control of the western waters. The bulkiness of their field and forest
products, fitted only for water transportation, and the immense mass of
downstream commerce called loudly for a maritime outlet and the
acquisition from Spain of some port at the Mississippi mouth. For twenty
years the politics of this transmontane country centered about the
"Island of New Orleans," and in 1803 saw its dream realized by the
Louisiana Purchase.

For the western trader, the Mississippi and Ohio were preeminently
downstream paths. Gravity did the work. Only small boats, laden with
fine commodities of small bulk and large value, occasionally made the
forty day upstream voyage from New Orleans to Louisville. Flat boats and
barges that were constructed at Pittsburg for the river traffic were
regularly broken up for lumber at downstream points like Louisville and
New Orleans; for the traders returned overland by the old Chickasaw
Trail to the Cumberland and Ohio River settlements, carrying their
profits in the form of gold. The same thing happens today, as it also
happened two thousand years ago, on the Tigris and Euphrates. The
highlander of Armenia or northern Mesopotamia floats down the current in
his skin boat or on his brushwood raft, to sell his goods and the wood
forming the frame-work of his primitive craft in timberless Bagdad and
Busra, as formerly in treeless Babylon. He dries out his skins, loads
them on his shoulders or on a mule brought down for the purpose, and
returns on foot to his highland village.[656] The same preponderance of
downstream traffic appears to-day in eastern Siberia. Pedlers on the
Amur start in the spring from Stretensk, 2025 miles up the river, with
their wares in barges, and drift down with the current, selling at the
villages _en route_, to the river's mouth