So we find that Lake Titicaca was the cradle of the Inca Empire, just as Lake Tezcoco was that of the Toltecs in Mexico and an island in Lake Chalco later that of the Aztec domain.[745] The most stable of the short-lived native states of Africa have apparently found an element of strength and permanence in a protected lake frontier.  Such are the petty kingdoms of Bornu, Bagirmi and Kanem on Lake Chad, and Uganda on Victoria Nyanza.

Large lakes, which include in their area islands, peninsulas, tides, currents, fiords, inlets, deltas, and dunes, and present every geographical feature of an enclosed sea, approach the latter too in historical importance.  Some of the largest, however, have long borne the name of seas.  The Caspian, which exceeds the Baltic in area, and the Aral, which outranks Lake Michigan, show the closest physical resemblance to thalassic basins, because of their size, salinity and enclosed drainage systems; but their anthropo-geographical significance is slight.  The very salinity which groups them with the sea points to an arid climate that forever deprives them of the densely populated coasts characteristic of most enclosed seas, and hence reduces their historical importance.  Their tributary streams, robbed of their water by irrigation canals, like “the shorn and parcelled Oxus”, renounce their function of highways into the interior.  To this rule the Volga is a unique exception.  Finally, cut off from union with the ocean, these salt lakes lose the supreme historical advantage which is maintained by freshwater lakes, like Ladoga, Nyassa, Maracaibo and the Great Lakes of North America, all lying near sea level.

[Sidenote:  Lakes as fresh water seas.]

Lakes as part of a system of inland waterways may possess commercial importance surpassing that of many seas.  This depends upon the productivity, accessibility and extent of their hinterland, and this in turn depends upon the size and shape of the inland basin.  The chain of the five Great Lakes, which together present a coastline of four thousand miles and a navigable course as long as the Baltic between the Skager Rack and the head of the Gulf of Bothnia, constitutes a freshwater Mediterranean.  It has played the part of an enclosed sea in American history and has enabled the Atlantic trade to penetrate 1400 miles inland to Chicago and Duluth.  Its shores have therefore been a coveted object of territorial expansion.  The early Dutch trading posts headed up the Hudson and Mohawk toward Lake Ontario, as did the English settlements which succeeded them.  The French, from their vantage point at Montreal, threw out a frail casting-net of fur stations and missions, which caught and held all the Lakes for a time.  Later the American shores were divided among eight of our states.  The northern boundaries of Indiana and Illinois were fixed by Congress for the express purpose of giving these commonwealths access to Lake Michigan.  Pennsylvania with great difficulty succeeded in protruding her northwestern frontier to cover a meager strip of Erie coast, while New York’s frontage on the same lake became during the period of canal and early railroad construction, a great factor in her development.