5. Perhaps the most important difference between the popular or theoretical and the statistical definition of immigrant is that the former is unchanging and the latter has been modified several times by changes of law or by modifications of administrative interpretation.
6. Until January 1, 1906, an alien arrival was counted as an immigrant each time he entered the country, but since that date an alien who has acquired a residence in the United States and is returning from a visit abroad is not classed as an immigrant. This administrative change has brought the statistical and the popular meanings of immigrant into closer agreement, but in so doing has reduced the apparent number of immigrants more than ten per cent. and has made it difficult to compare the earlier and the later statistics.
7. Until January 1, 1903, an alien arriving in the first or second cabin was not classed as an immigrant, but rather under the head of other alien passengers. This change likewise brought the two meanings of immigrant into closer agreement, but also made it difficult to compare the figures before and after that date. By a mere change of administrative definition the reported number of immigrants was increased nearly twelve per cent.
8. Until the same date an alien arrival in transit to some other country was deemed an immigrant, but since that date such persons have been classed as non-immigrant aliens. This change also makes the figures before 1903 not strictly comparable with later ones. About three per cent. of those who were formerly classed as aliens have been excluded since 1903. The alteration has brought the two definitions closer together, but in so doing has entailed administrative difficulties which lead the bureau to favour a return to the former system or at least to favour collecting the head tax from such aliens in transit.
9. An immigrant in the statistical sense is a person liable for and paying the head tax. But to this there are two slight exceptions. Deserting alien seamen not apprehended are liable for the head tax which is paid by the company from which they desert, but such cases are not included in the statistics. Citizens of British North America, Cuba and Mexico coming from other ports than those of their own country are reported as immigrants, but do not pay the head tax. Obviously both are minor exceptions hardly affecting the rule. In the popular or theoretical meaning of immigrant this head tax is not an element.