e stability of their tenure, and hence the equilibrium of
the pressure upon the boundary. Therefore, in such countries, racial,
linguistic and cultural boundaries tend to become simpler and
straighter.

[Sidenote: The broad frontier zone of active expansion.]

The growth is more apparent, or, in other words, the border zone is
widest and most irregular, where a superior people intrudes upon the
territory of an interior race. Such was the broad zone of thinly
scattered farms and villages amid a prevailing wilderness and hostile
Indian tribes which, in 1810 and 1820, surrounded our Trans-Allegheny
area of continuous settlement in a one to two hundred mile wide girdle.
Such has been the wide, mobile frontier of the Russian advance in
Siberia and until recently in Manchuria, which aimed to include within a
dotted line of widely separated railway-guard stations, Cossack
barracks, and penal colonies, the vast territory which later generations
were fully to occupy. Similar, too, is the frontier of the Dutch and
English settlements in South Africa, which has been pushed forward into
the Kaffir country--a broad belt of scattered cattle ranches and
isolated mining hives, dropped down amid Kaffir hunting and grazing
lands. Broader still was that shadowy belt of American occupation which
for four decades immediately succeeding the purchase of Louisiana
stretched in the form of isolated fur-stations, lonely trappers' camps,
and shifting traders' _rendezvous_ from the Mississippi to the western
slope of the Rockies and the northern watershed of the Missouri, where
it met the corresponding nebulous outskirts of the far-away Canadian
state on the St. Lawrence River.

The same process with the same geographical character has been going on
in the Sahara, as the French since 1890 have been expanding southward
from the foot of the Atlas Mountains in Algeria toward Timbuctoo at the
cost of the nomad Tuaregs. Territory is first subdued and administered
by the military till it is fully pacified. Then it is handed over to the
civil government. Hence the advancing frontier consists of a military
zone of administration, with a civil zone behind it, and a weaker
wavering zone of exploration and scout work before it.[337] Lord Curzon
in his Romanes lecture describes the northwest frontier of India as just
such a three-ply border.

[Sidenote: Economic factors in expanding frontiers.]

The untouched resources of such new countries tempt to the