40-year pause in immigration to the United States was that two generations of young people grew up having very little contact with immigrants. At the end of World War II, the United States population was nearly 90 percent white (U.S. Census Bureau, 1961). Outside of areas in the rural South, and some northern cities where African Americans had migrated to escape the Southern Black Codes and Jim Crow laws, and outside of Mexican-American communities along the U.S.-Mexico border, and areas near Native American reservations, the average white American was unlikely to encounter many people who weren't fellow white American.
