of his frontier environment and found
a multitude of his kind in that region of backwoods farms to follow him
into the wilderness. Thomas Jefferson of Virginia, in the Louisiana
Purchase, carried out the policy of expansion adumbrated in Governor
Spottswood's expedition with the Knights of the Golden Horseshoe over
the Blue Ridge in 1712. Jefferson's daring consummation of the purchase
without government authority showed his community of purpose with the
majority of the people. Peter the Great's location of his capital at St.
Petersburg, usually stigmatized as the act of a despot, was made in
response to natural conditions offering access to the Baltic nations,
just as certainly as ten centuries before similar conditions and
identical advantages led the early Russian merchants to build up a town
at nearby Novgorod, in easy water connection with the Baltic
commerce.[74]

[Sidenote: Economic and social effects.]

III. Geographic conditions influence the economic and social development
of a people by the abundance, paucity, or general character of the
natural resources, by the local ease or difficulty of securing the
necessaries of life, and by the possibility of industry and commerce
afforded by the environment. From the standpoint of production and
exchange, these influences are primarily the subject matter of economic
and commercial geography; but since they also permeate national life,
determine or modify its social structure, condemn it to the dwarfing
effects of national poverty, or open to it the cultural and political
possibilities resident in national wealth, they are legitimate material
also for anthropo-geography.

[Sidenote: Size of the social group.]

They are especially significant because they determine the size of the
social group. This must be forever small in areas of limited resources
or of limited extent, as in the little islands of the world and the yet
smaller oases. The desert of Chinese Turkestan supports, in certain
detached spots of river-born fertility, populations like the 60,000 of
Kashgar, and from this size groups all the way down to the single
families which Younghusband found living by a mere trickle of a stream
flowing down the southern slope of the Tian Shan. Small islands,
according to their size, fertility, and command of trade, may harbor a
sparse and scant population, like the five hundred souls struggling for
an ill-fed existence on the barren Westman Isles of Iceland; or a
comp