1850 10,715 1860 15,157 1870 16,875 1880 15,365 1890 17,314 1900 15,886 1910 17,227 It thus appears that the proportion of foreign-born, even at the time of the census of 1900, after a decade of very slight immigration, was much higher than at the time of the beginning of large immigration, while the last census, after the enormous immigration of the past ten years, shows a proportion of foreign-born higher than at any previous census, except that of 1890. Now it is the proportion of foreign-born to native-born which determines the assimilating power of the nation, so that without this correction the comparison between immigration and total population is inadequate and misleading. It is as if a fireman whose steam boiler lacked a safety valve was warned that his gauge was going up more and more rapidly all the time, and he replied, “Never mind, the pressure is not coming in so fast, compared to what I already have, as it was awhile ago.” Another circumstance which affects the ability of the country to assimilate immigrants, and in which there has been a marked change during the history of immigration, is the ratio of men to land, upon which much emphasis has already been laid. As the amount of unappropriated and unsettled land diminishes in any country, the need of new settlers also diminishes, while the difficulty of assimilation and the possible evils resulting from foreign population proportionally increase. In the case of the United States the first and simplest comparison to make is that between immigration and the total territory of the nation. In this, as in the subsequent comparisons, it will be desirable to leave Alaska out of consideration. The enormous extent of that inhospitable region, to which practically none of our immigrants ever find their way, if included in the reckoning, would simply confuse the issue. The gross area of the United States, exclusive of Alaska and Hawaii, at the time of the different censuses, has been as follows: 1790 and 1800, 827,844 square miles; 1810, 1,999,775 square miles; 1820, 2,059,043 square miles; 1830 and 1840, the same; 1850, 2,980,959 square miles; 1860 down to the present, 3,025,600 square miles.[340] Estimating the immigration before 1820 at 10,000 per year, and using the official figures after that date, we find that the immigration by decades from 1791 to 1910 was as follows: