San Francisco is a major city in northern California located on a peninsula between the Pacific Ocean and the San Francisco Bay. The city is roughly 46 square miles and home to landmarks such as the infamous Alcatraz Island (former maximum security prison). The African American population of San Francisco was about 4,000 persons before WWII. After WWII, with the onset of the Great Migration("a mass movement by Black Americans in the early 20th century from the predominantly rural, segregated South, to the urban North and West, where they sought greater economic, social, and political freedom"), the Black population increased 24-fold. The migrants were attracted by the ample number of jobs available in the Bay Area's shipyards and other industries.