Oakland is a major West Coast port city in the U.S. state of California. The Port of Oakland is the busiest port for San Francisco Bay and all of Northern California. 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 U.S. with a population of 390,724 as of 2010. Incorporated in 1852, Oakland is the county seat of Alameda County. It serves as a major transportation hub and trade center for the entire region and is also the principal city of the Bay Area Region known as the East Bay. The city is situated directly across the bay, six miles (9.7 km) east of San Francisco.Oakland's territory covers what was once a mosaic of 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. It continued to grow in the 20th century with its busy port, shipyards, and a thriving automobile manufacturing industry. Following the 1906 San Francisco earthquake, many San Franciscans relocated to Oakland, enlarging the city's population, increasing its housing stock and improving its infrastructure.