After the First World War, migration from Europe was on a much smaller scale. In 1921 new rules restricted the number of immigrants allowed from each country — and favoured northern Europeans. They allowed less than 6,000 people a year from Italy, but ten times as many from Britain — though the quotas were amended after 1929. But soon the great depression, then the Second World War, played their part in restricting the flow further still, and since then the small numbers coming from Europe have been very different from the earlier generations. Professors, engineers, scientists and doctors have come, particularly from Britain, to better conditions of work and much higher play than they would find in Europe. Intellectuals and specialists of every kind have brought their special skills to reinforce American History, commerce, education, research, arts and entertainment. Many of these people have received their education and training at the expense of the taxpayers of their own home countries.
Even among these well-qualified people, some have been refugees from persecution. It would be hard to find a single group who have brought such benefits to America as the Jews who escaped from Nazi Germany and Austria, many of them after experiencing great difficulties, both at home and on the way. After 1945 there were other refugees from central Europe, many of them intellectuals or former members of what the new rulers called the bourgeoisie. In the turmoil caused by the political changes of that time it was not practicable to operate a national quota system along with an open door for refugees; but the total numbers admitted to, the United States were small when compared with those of fifty years before.
Immigration from Europe has declined even more since the 1950s, though the flow of doctors, nurses and scientists from Britain causes anxiety in that country about what is called the ‘brain drain’ Fewer European settlers came in the fifteen years from 1970 to 1985 than in the one year of 1907. One reason for the change is the increasing prosperity of Western Europe, another the difficulty of leaving Eastern Europe. But there are plenty of people from Europe living temporarily in the United States, with permits to work but not to stay indefinitely. There is not only a 'brain drain' to America, but also a continuous flow both ways across the Atlantic as professors and managers make their careers partly on one side, partly on the other, bringing America and Europe closer to each other. Meanwhile, the main sources of immigration have been increasingly outside Europe, mainly Central America and the Caribbean but also Asia, and to a lesser extent, Africa.
Chinese and Japanese communities had been established, mainly in the western cities, before 1900, and later fed by a small trickle across the Pacific, both before and after the quota system had been set up. By the 1960s quite large numbers had come from the American Caribbean island of Puerto Rico, and then, after 1959, many thousands of opponents of the new regime in Cuba were accepted as refugees. At that time it was widely felt that the old immigration policy had been 'racist'. In response to this, quotas for countries in Africa and Asia were increased, or allowed for the first time.
One and a half million people came from Asia in the 1970s, ten times as many as in the 1950s, and the flow from Asia grew in the 1980s. In 1985 a quarter of a million immigrants came from Asia, four times as many as from the whole of Europe. Although the Asians arriving since 1975 have included refugees from Vietnam, there have been far more from the other countries bordering the Pacific Ocean, including a few accepted as refugees fleeing political persecution. But the biggest source of immigrants since the 1960s has been Latin America, particularly Mexico — and among the people from Mexico the biggest element has probably been illegal, outside any quota or effective check or count. The two thousand kilometre border between the United States and Mexico is not very difficult to cross. There are no mines or other frightening obstacles. There are guards, but they do not shoot. Every year they catch tens of thousands trying to cross and send them back — but tens of thousands of others make their way without being caught. They are not all Mexicans; some come through Mexico from Guatemala or further south.
According to the official figures, the United States has lately been receiving about half a million immigrants a year; twice as many as in the 1950s, but only half the peak of the early 1900s. But these figures do not include the uncounted people who cross from Mexico illegally. Officially the total of around 200,000 coming from Latin America as a whole includes some 60,000 from Mexico, but it is generally believed -that the true figure is several times as great. On the other hand, even if the true total of people trying to escape from homeland poverty is as great as a hundred years ago, it is still much less in relation to the already settled population. Also, just as it is much easier to cross the border from Mexico unseen than it is to escape notice when arriving by an intercontinental air service or ocean-going ship, so it is easy to go back again after a few months or years of working for wages much higher than can be earned at home. Many of the illegal immigrants do in fact stay in the United States, but the people who return to their own home countries are not really immigrants at all.
In 1987 a new form of indirect control of immigration was brought into effect, against the wishes of some business interests as well as humanitarian liberals. It became a punishable offence to employ people without proper documentation. In the next few months the number of people caught trying to enter the U.S. illegally from Mexico declined. Meanwhile, people who can show that they have worked in the U.S. for five years can apply for, and normally obtain, documents entitling them to stay and eventually to apply for naturalisation as U.S. citizens.