rease of population
adequate for higher industrial development and for defence.

A race boundary involves almost inevitably a cultural boundary, often,
too, a linguistic and religionary, occasionally a political boundary.
The last three are subject to wide fluctuation, frequently overstepping
all barriers of race and contrasted civilizations. Though one often
accompanies another, it is necessary to distinguish the different kinds
of boundaries and to estimate their relative importance in the history
of a people or state. We may lay down the rule that the greater, more
permanent, and deep-seated the contrasts on the two sides of a border,
the greater is its significance; and that, on this basis, boundaries
rank in importance, with few exceptions, in the following order: racial,
cultural, linguistic, and political. The less marked the contrasts, in
general, the more rapid and complete the process of assimilation in the
belt of borderland.

[Sidenote: The boundary zone in political expansion.]

The significance of the border zone of assimilation for political
expansion lies in the fact that it prepares the way for the advance of
the state boundary from either side; in it the sharp edge of racial and
cultural antagonism is removed, or for this antagonism a new affinity
may be substituted. The zone of American settlement, industry, and
commerce which in 1836 projected beyond the political boundary of the
Sabine River over the eastern part of Mexican Texas facilitated the
later incorporation of the State into the Union, just as a few years
earlier the Baton Rouge District of Spanish West Florida had gravitated
to the United States by reason of the predominant American element
there, and thus extended the boundary of Louisiana to the Pearl River.
When the political boundary of Siberia was fixed at the Amur River, the
Muscovite government began extending the border zone of assimilation far
to the south of that stream by the systematic Russification of
Manchuria, with a view to its ultimate annexation. Schleswig-Holstein
and Alsace-Lorraine, by reason of their large German population, have
been readily incorporated into the German Empire. Only in Lorraine has a
considerable French element retarded the process. The considerable
sprinkling of Germans over the Baltic provinces of Russia and Poland
west of the Vistula, and a certain Teutonic stamp of civilization which
these districts have received, would greatly facilitate the ea