ge immigration occurred, the decennial
rates of increase of the population were almost the same as in the
three decades from 1800 to 1830.[7] The conclusion drawn from these
figures is that the immigrants were the cause of the decline of the
average birthrate that occurred in the families of native stock. The
validity of this conclusion is absolutely dependent on the assumption
that no other forces were at work to produce this result. Must we
believe that, but for immigration, the native birthrate would not have
declined at all? This is incredible. The birthrate of the native stock
had already begun to decline before 1820 as is shown by many family
records, and by the fall of the decennial rate of increase from 35 and
36 in the decades ending 1800 and 1810, to 33.1 and 33.5 in the next
two decades. This occurred despite the enormous western settlement
then under way on the Louisiana Purchase. The decline of the birthrate
began at that time to appear as a world-wide phenomenon, accompanying
improved transportation (roads, steamboats, steam railways), the rapid
growth of cities, and the general industrial revolution. The general
birthrate has declined of recent years in Australia and New Zealand,
where there has been little immigration, more rapidly than it has in
the United States.[8]

Sec. 11. #Magnitude of the inflow of immigrants.#In view of these facts
it seems necessary to modify the displacement theory greatly. To the
extent that the coming of immigrants caused a net addition to the
population, it doubtless hastened the growth of cities and the
development of industrialism, and thus helped to reduce the birthrate
in some classes. But this view admits the effect upon population which
the displacement theory denies. Probably, in a good many cases the
more rapid business advancement of the natives, because of the
coming of the immigrants, led to the decline of birthrate that is a
consequence of economic success.[9] But a large part of this change
would have inevitably occurred even if there had been no immigration
after 1820. Between 1820 and 1910 the population increased 82,400,000,
and the total number of immigrants was 27,800,000, or 33.7 per cent
of the total increase. In an urban environment the birthrate among
immigrants always has been very much higher than that of native
Americans. This fact alone might well be taken as sufficient to offset
whatever depressing effects the coming of the immigrants may have
had