Oakland/ˈoʊklənd/ is the largest city and the county seat of Alameda County, California, United States. A major West Coast port city, Oakland is the third largest city in the San Francisco Bay Area, the eighth-largest city in California, and the 45th-largest city in the country, with a population of 419,267 as of 2015. It serves as a trade center for the San Francisco Bay Area; its Port of Oakland is the busiest port in the San Francisco Bay, all of Northern California, and is the fifth busiest in the United States. Incorporated in 1852, Oakland is also the principal city of the Bay Area Region known as the East Bay. The city is located six miles (9.7 km) east of San Francisco.
Oakland's territory covers what was once a mosaic of California coastal terrace prairie, oak woodland, and north coastal scrub. Its land served as a rich resource when its hillside oak and redwood timber were logged to build San Francisco, and Oakland's fertile flatland soils helped it become a prolific agricultural region. In the late 1860s, Oakland was selected as the western terminal of the Transcontinental Railroad. Following the 1906 San Francisco earthquake, many San Francisco citizens moved to Oakland, enlarging the city's population, increasing its housing stock and improving its infrastructure. It continued to grow in the 20th century with its busy port, shipyards, and a thriving automobile manufacturing industry.
Oakland is known for its sustainability practices, including a top ranking for usage of electricity from renewable resources. Oakland is also 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. In addition, due to 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, Oakland is one of the most ethnically diverse major cities in the country.