chief growth during the past forty years has been in
the valley lands. In that time if the uplands have not suffered actual
loss, they certainly have made no material gains. Upland farming has not
proved a remunerative venture, and many of the farms have either been
abandoned or converted to other uses.

=Passes.=--Transverse valleys form very important topographic features of
mountain-regions. Inasmuch as the ranges themselves are obstacles to
communication, it follows that the latter must be concentrated at such
cross valleys or gaps as may be traversed. Khaibar Pass, a narrow defile
in the Hindu Kush Mountains, between Peshawur and Jelalabad, for many
years was the chief gateway between Europe and India. Even now the cost
of holding it is an enormous tax upon England.

Brenner, St. Gotthard, and the Mont Cenis Passes are about the only land
channels of commerce between Italy and transalpine Europe, and most of
the communication between northern Italy and the rest of Europe is
carried on by means of these passes. Every transcontinental railway of
the American continent crosses the various highlands by means of gaps
and passes, and some of them would never have been built were it not for
the existence of the passes. Fremont, South, and Marshall Passes have
been of historic importance for half a century.

The Hudson and Champlain Valley played an important part in the history
of the colonies a century before the existence of the United States, and
its importance as a gateway to eastern Canada is not likely to be
lessened. The Mohawk gap was the first practical route to be maintained
between the Atlantic seaboard and the food-producing region of the Great
Central Plain. It is to-day the most important one. It is so nearly
level that the total lift of freight going from Buffalo to tide-water is
less than five hundred feet.

[Illustration: A PASS--THE ROUTE OF A RAILWAY]

=Rivers.=--River-valleys are closely connected with the economic
development of a country. Navigable rivers are free and open highways of
communication. In newly settled countries the river is always the least
expensive means of carriage, and often it is the only one available for
the transportation of heavy goods.

In late years, since the railway has become the chief means for the
transportation of commodities, river transportation has greatly
declined. The river-valley, however, has lost none of its importance; in
most instances it is a naturally