nly the eastern margin of this area was
at all fully settled; and the population numbered at most 2,000,000,
predominantly of British blood. In 1803, by a treaty with Napoleon, the
French colony of Louisiana, with vast and ill-defined claims to the
territory west of the Mississippi, was purchased from France. Meanwhile
the stream of immigrants from the eastern states, and in a less degree
from Europe, was pouring over the Alleghany Mountains and occupying the
great central plain; and by 1815 the population had risen to almost
9,000,000, still mainly of British stock, though it also included
substantial French and German elements, as well as large numbers of
negro slaves. In 1819 Florida was acquired by purchase from Spain. In
1845-48 a revolution in Texas (then part of Mexico), followed by two
Mexican wars, led to the annexation of a vast area extending from the
Gulf of Mexico to the Pacific coast, including the paradise of
California; while treaties with Britain in 1818 and 1846 determined the
northern boundary of the States, and secured their control over the
regions of Washington and Oregon.

Thus the imperialist spirit was working as irresistibly in the
democratic communities of the New World as in the monarchies of Europe.
Not content with the possession of vast and almost unpeopled areas,
they had spread their dominion from ocean to ocean, and built up an
empire less extensive indeed than that of Russia, but even more
compact, far richer in resources, and far better suited to be the home
of a highly civilised people. Into this enormous area there began to
pour a mighty flood of immigration from Europe, as soon as the
Napoleonic wars were over. By 1878 the population of the States had
risen to about 50,000,000, and was greater than that of any European
state save Russia. A new world-state of the first rank had arisen. It
was made up of contributions from all the European peoples. Those of
British stock, especially the Irish, still predominated throughout this
period, but the Germans and the Scandinavians were becoming
increasingly numerous, and the Italians, Greeks, Poles, Czechs, Russian
Jews, and other stocks were beginning to form very substantial
elements. It was a melting-pot of races, which had to be somehow welded
into a nation by the moulding-power of the traditions implanted by the
earlier British settlers. It may fairly be said that no community has
ever had imposed upon it a more difficult task than the