Oakland has the 5th largest container port in the U.S. which is a good reason it is interesting to railfans. But saying it is disproportionately black is dead wrong. Oakland has pockets that are mostly a single ethnic group (e.g., European Americans, Chinese Americans, and African Americans) and low or high income areas, but as a whole, most areas are a interesting mix of cultures. Here is a Wikipedia paragraph:

The 2010 United States Census reported that Oakland had a population of 390,724. The population density was 5,009.2 people per square mile (1,934.0/kmē). The racial makeup of Oakland was 134,925 (34.5%) White, 109,471 (28.0%) African American, 3,040 (0.8%) Native American, 65,811 (16.8%) Asian (8.7% Chinese, 2.2% Vietnamese, 1.6% Filipino, 0.7% Cambodian, 0.7% Laotian, 0.6% Korean, 0.5% Japanese, 0.5% Indian), 2,222 (0.6%) Pacific Islander, 53,378 (13.7%) from other races, and 21,877 (5.6%) from two or more races. Hispanic or Latino of any race were 99,068 persons (25.4%). Among the Hispanic population, 18.1% are Mexican, 1.9% Salvadoran, 1.3% Guatemalan, and 0.7% Puerto Rican.

See for answers to many of the questions asked:
[en.wikipedia.org]