With the disappearance of the frontier of free land, agitation for restriction of immigration began to appear. The newer immi grants, as already indicated, crowded into the cities, creating vast problems of assimilation and housing, and their competition with the native labourer was more keenly felt, now that the latter had no frontier to which to escape. The problem became more acute after the World War, when the United States, faced with the problem of reabsorbing its own war veterans into normal industrial life, realized that some barrier should be erected to restrict immigration from Europe. Immigration increased from 141,132 in the year ending June 3o, 1919, to 805,228 in 1921. (For re striction since 1921, see MIGRATION.) Following somewhat lower figures in 1922 and 1923, immigra tion had risen again in 1924 to 706,896. In this year the Immi gration Act of 1924 went into effect, with the result that in 1925 only 294,314 immigrant aliens were admitted to the United States. The numbers admitted in the next few years were around 300,000, but further restrictions imposed as a result of the de pression reduced the number admitted in 1931 to 97,139. In 1932, admissions fell still further to 35,576, and in 1933 to the minimum of 23,068, though the increases since 1933 have been relatively small.
Attention has already been called to the fact that during the four years from 1932 to 1935 the number of emigrants from the United States exceeded the number of immigrants.
The number of immigrant aliens admitted during the calendar year 1937 was 62,613, of which number 14,866 came from Canada, 13,643 came from Germany, 7,938 came from Italy, 2,602 came from Czechoslovakia, 2,56o came from Mexico, and from the United Kingdom, 2,385.
Table III shows the urban population—that is, the population in incorporated places of 2,500 or more—and the numbers of places of various size included therein for the 15 decennial cen suses of the United States from 1790 to 1930.
. . Total and Urban Population of the United States: 1790 to 193o The urban trend from 1820 to 1930 is shown graphically in fig. 2, which not only indicates the rapid increase in the relative
importance of the urban population during recent decades, but also shows effectively that for the major part of the nation's history it has been dominantly rural, with the half-way point (half rural and half urban) reached just before 1920. There is also presented on this figure a line indicating the percentage of all gainful workers engaged in non-agricultural occupations. Since this line runs almost parallel with the line of urban population, it may be assumed that the increase in the relative importance of occupations other than farming was one of the important under lying causes of the growth of the urban population.
Up to 1830 the percentage of the population urban increased very slowly, which means that the growth of the urban popula tion was little more rapid than that of the rural. Between 1830 and 1840 the percentage urban in the country as a whole in creased from 8.8 to io.8, or by not quite one-fourth. In many individual States, however, the increase during this decade was much greater, the percentage urban in 1840 in some cases doubling that in 1830.
Between 1840 and 1850 the percentage urban in the country as a whole increased from 10.8 to 15.3, or by nearly one-half. This relative increase was exceeded in several of the older States, in cluding Maine, New Hampshire, New Jersey and New York, but the most notable increases in urbanization during this period were in some of the newer States.
In the State of Ohio, for example, the percentage urban in creased from 5.5 to 12,2; in Indiana, from 1.6 to 4.5; in Illinois, from 2.0 to 7.6; in Michigan, from 4.3 to 7.3; and in Missouri, from 4.3 to 11.8.
By 185o, settlement was well under way in most of the States which have now attained a high percentage of urban population, and since that date the trend of the percentage urban in the country as a whole has been less affected by the expansion of the settled area, or by the beginning of urbanizatio'n in the newer States, than it was in the decades preceding 185o.
In 1930 there were 21 States in which more than one-half of the population was urban. The census dates on which these States were first shown to have more than one-half of their population living in urban territory may be of some significance as indicating the geographic progress of urbanization over the country. Massa chusetts and Rhode Island were the first of these States, their population being returned as more than so% urban in 185o. New York was added to the list in 1870; New Jersey in 188o; Connecti cut in 1890; and in 1900, Pennsylvania, Illinois and California.