migrations were, moreover, somewhat different from modern immigration
and emigration. Ancient migrations were largely those of peoples or
tribes, while in modern times migration is more of an individual matter.
The Huns, for example, came into Europe as a nation, but the immigration
into the United States at the present time is wholly an individual
movement. The causes of migration are more or less universal, but
corresponding to the difference in ancient and modern migrations we find
the causes varying somewhat in ancient and modern times. The causes of
ancient migrations and the primary causes of all migrations seem to be:
(1) lack of food; (2) lack of territory for an expanding population; (3)
war. In modern times we find other causes operating, like, (4) the labor
market; men now migrate chiefly to get better economic opportunities;
(5) government; in modern times the oppression of unjust governments has
often caused extensive migration; (6) religion; religious persecution
and intolerance have in modern times been important among the causes of
migration.

History of Immigration into the United States.--The great economic
opportunities offered by the settlement of the vast territory of the
United States, together with a combination of causes in Europe, partly
political, partly religious, and partly economic, have caused, during
the last century, a flood of immigrants from practically all European
countries, to invade the United States, greater in number of individuals
than any recorded migration in history. Between 1820, the first year for
which we have immigration statistics, and 1907, 25,318,000 immigrants
sought homes, temporarily or permanently, in this country,--more than
one half of them coming since 1880. Before 1820 it is improbable that
immigration into the United States assumed any large proportions. Even
up to 1840 the number of immigrants was comparatively insignificant.
Thus in 1839 the number was only 68,000, and not until 1842 did the