From Peter Brimelow’s 1993 op-ed in the London Times:
[T]he rationale for the post-1965 immigration influx is that America is not a nation-state in the European sense. Instead, it is said to be an “idea”, a political construct based on adherence to a written constitution, without any specific cultural, ethnic or linguistic content.
That rationale is unhistorical. It would have astonished Theodore Roosevelt, president during the last great immigration influx, whose many books explicitly celebrated the link between the Anglo-Saxon invasion of England and their descendants’ winning of the American West. When President Coolidge signed the legislation ending the last influx in the 1920s, he explained his reason succinctly: “America must be kept American.” Everyone knew what he meant.
Although US immigration policy is irrational, the political establishment resists discussion of it. The reasons are various. Some will be familiar to British observers; others reflect peculiar American pressures. We may be watching America heaping up its funeral pyre, to use Mr. Powell’s phrase. Or perhaps a launching pad to becoming the “first universal nation”. Whatever it is, it looms increasingly large.