The rapid mobilization of resources and weapons during World War II prompted many African Americans to migrate to Northern and Western cities in search of jobs in the booming munitions industry. While the Northern black communities such as Chicago and New York City were already well-established from the first Great Migration, relocating to the West was a new destination for the migrants in places like the San Francisco Bay Area, Los Angeles, Portland, Phoenix, and the Puget Sound region in Washington. 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 migration. 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.