In the same way, when the early French explorers and traders of Canada reached the hydrographic center of the continent about Lakes Superior and Michigan, they quickly crossed the low rim of these basins southward to the Mississippi, and northward to the Rainy Lake and Winnipeg system draining to Hudson Bay.[655] While 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 at Nikolaievsk.  Here they dispose of their remaining stock and also of their barges, the lumber of which is utilized for sidewalks, and they themselves return upstream by