A steady influx of immigrants during the 20th century, along with thousands of African-American war-industry workers who relocated from the Deep South during the 1940s, have made Oakland one of the most ethnically diverse major cities in the country. Oakland is known for its history of political activism, as well as its professional sports franchises and major corporations, which include health care, dot-com companies and manufacturers of household products. The city is a transportation hub for the greater Bay Area, and its shipping port is the fifth busiest in the United States.
