SIGNIFICANT FEATURES OF MIGRATION 51 
alien arrivals to each one thousand population. By 1920, the in- 
coming flow was gaining momentum and in the fiscal year of 1921 
reached almost a pre-war level at 0.9 per cent. The depression of 
1921 brought a marked reduction in the ratio during the fiscal year 
1922, but in the two subsequent years, despite the restrictions of 
the three per centum quota law, the annual volume increased to 
over one-half of one per cent of the population. 
Net arrivals exceeded one per cent of the population only in 
1907, was relatively low in the depression years (fiscal) of 1904, 
1908, 1911-1912, and particularly 1922, and, in some of the war 
years almost reached the vanishing point. In the year ending 
June 30, 1924, they had rallied, despite restrictive legislation, to 
over one-half of one per cent of the estimated population on Jan- 
uary 1, 1924. 
It may well be questioned whether a comparison between total 
immigration and total population is the most significant for our 
purposes. As we are concerned with the contribution of immigra- 
tion to the supply of labor, a more significant ratio is obtained by 
comparing the number of alien arrivals (excluding those recorded 
as having “no occupation’) with the estimated total number of 
gainfully employed in the United States. It might be even more 
pertinent to compare arrivals with the number of gainfully em- 
ployed in those sections of the country in which the aliens settle in 
large numbers, but for the present at least we shall rest content 
with the comparison based upon data for the entire country. 
Arriving aliens are classified according to the occupations followed 
in their home countries. Those, including women and children, 
who have no gainful occupations are placed in a “no occupation” 
group, the remainder, exclusive of the “no occupation” group, may, 
with substantial accuracy, be designated as “working immigrants.” 
Though many immigrants ultimately become independent farmers 
or set up in business for themselves, the great bulk of them, par- 
ticularly in the period immediately after their arrival, become 
wage earners in factories, mines, building construction, or on farms. 
Consequently, an appropriate standard with which to compare the 
number of “working immigrants” is the number of wage earners in 
industry. In Table 11 such a comparison has been made between 
the gross and net arrivals of alien workers and the estimated num- 
ber of wage earners attached to the leading industries. The workers 
considered “attached” to a given industry are those who look to 
that industry as their chief occupation, although they may be