Why did some Americans become nativists and urge restrictions on immigration?

 Many "old stock" Americans were troubled by the vast number of immigrants from Southern and Eastern Europe. Some Americans of Anglo-Saxon descent harbored prejudice against residents of Southern and Eastern Europe. Many Protestants disliked Catholics and Jews. And some "old stock" Americans associated recent immigrants with socialism, anarchism, and other radical political views. For all of these reasons, many native-born Americans feared that immigration threatened America's traditions, as well as its economic and political stability. Opponents of immigration were called nativists, who believed that the U.S. government should protect the interests of native-born citizens, rather than allow unrestricted immigration.

Nativism was especially strong when the U.S. economy fared poorly (as it did in the 1870s and 1890s) and during World War I, when some Americans feared that a wave of refugees would flee the war in Europe for America. The American Protective Association, a nativist organization, was founded in 1887. By 1894, it had more than 500,000 members. The association claimed to support "true Americanism," and urged "America for the Americans." Its members opposed Catholicism (especially when Catholics ran for political office) and advocated severe limits on the number of immigrants allowed into the U.S., and insisted that immigrants should be "Americanized"--that is, encouraged to shed their original ethnic culture and identity in order to blend into the American melting pot.