 The city's formerly most populous ethnic group, whites, declined from 95.3% in 1940 to 32.5% by 1990, due to a combination of factors, including suburbanization.Oakland became a destination for African Americans in the Great Migration during and after World War II as they gained high-paying jobs in the defense industry.Blacks have formed a plurality in Oakland for many years, peaking in 1980 at about 47% of the population.