<P> The lack of opportunity in the South prompted many African Americans to migrate to Western cities in search of jobs in the booming munitions industry . Once they arrived, they were met with a variety of factors that separated emerging migrant communities from white ones . This urban spatial segregation led to the creation of racially homogeneous areas in cities that saw large amounts of African American immigration, such as the San Francisco Bay and Los Angeles . It is estimated that less than 1% of Los Angeles's 461,000 black residents lived in communities without a black majority in 1960, resulting in de facto segregation . In order to exploit the poor financial situation many migrants were in, areas of low income housing were established in places city planners wanted them to live . For example, South Los Angeles was established as a designated area for African Americans as early as the 1930s . Working class blacks were attracted by the low price of housing intentionally placed in order to encourage the concentration of blacks and Latinos away from whites . Freeways were often built with the isolation of racial communities in mind . They served to reinforce lines of segregation and further contributed to the isolation of racially homogeneous communities in racially diverse cities . The fear of racially motivated violence and discrimination also served to isolate communities of minorities as they sought collective security and nondiscriminatory treatment close to home . The limited amount of housing, combined with the upsurge of immigrants during the Second Great Migration lead to severe overcrowding and housing shortages that contributed to increasingly low property values . </P> <P> As property values within these communities plummeted, the middle class, mostly white residents of target areas evacuated en masse . This is a phenomenon known as white flight . The introduction of non-white residents into a traditionally white area, in this case, inner city neighborhoods, caused the rapid evacuation of whites, usually to the suburbs . In this way, the common social trope of white suburbia and the racially diverse inner city came to be . It is currently estimated that over 70% of blacks operating in a given metropolitan area live in the city center . Comparatively, only 30% of whites operating within that same city live in the inner city . White flight was driven in part by the process of blockbusting . White property owners, fearful of minority groups, sold their homes to real estate agents at a low price, often due to the tactics of the real estate companies themselves . Agents would then encourage that the vacant properties be bought by black families seeking respite from the overcrowded neighborhoods in which they were sequestered . When one black family moved in, the white neighbors would immediately sell their homes to the waiting real estate companies, who would in turn sell to more black people at a significant markup . </P> <P> Another obstacle facing migrating blacks were the discriminatory housing laws that were put in place to counteract progressive legislation in California following World War II . The 1963 Rumford Fair Housing Act that outlawed discrimination in housing was effectively nullified by California Proposition 14 in 1964 . This legislation, sponsored by the California Real Estate Association and conservative state institutions, affirmed the property owner's right to refuse to sell, rent or lease their property based solely on race . The federal government immediately cut funding to California housing and both the California and United States Supreme Court declared Prop 14 unconstitutional . It was officially repealed by California Proposition 7 in 1974, but while it was in practice it contributed to the segregation of black migrants and is cited as a direct cause of the Watts riots in 1965 . </P> <P> The effect of racially homogeneous communities composed largely of migrant blacks that formed because of spatial segregation in destination cities was that they were largely influenced by the Southern culture they brought with them . The food, music and even the discriminatory white police presence in these neighborhoods were all imported to a certain extent from the collective experiences of the highly concentrated African American migrants . </P>

What caused the urban migration in the united states