As European demographic vitality waned in the 1990s, a surge of migrants from Africa, Asia, and the former Soviet Bloc headed for western Europe. Some migrants entered the European Union legally, but increasing numbers were smuggled in. Large-scale immigration, both documented and undocumented, emerged as a critical and controversial issue.

Western Europe saw rising numbers of immigration in postcolonial population movements beginning in the 1950s, augmented by the influx of manual laborers in its boom years from about 1960 until about 1973 (see "Patterns of Postwar Migration" in Chapter 28). A new and different surge of migration into western Europe began in the 1990s. The collapse of communism in the East Bloc and savage civil wars in Yugoslavia drove hundreds of thousands of refugees westward. Equally brutal conflicts outside Europe brought thousands more. Undocumented immigration into the European Union also exploded, rising from an estimated 50,000 people in 1993 to perhaps 500,000 a decade later, far exceeding the estimated 300,000 unauthorized foreigners entering the United States each year.