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 eastward extension of the German Empire; while their common religions, both Protestant and Roman Catholic, would help obliterate the old political fissure. Thus the borderland of a country, so markedly differentiated from its interior, performs a certain historical function, and becomes, as it were, an organ of the living, growing race or state. [Sidenote: Tendency toward defection along political frontiers.]