The San Francisco–Oakland Bay Bridge, commonly referred to as the Bay Bridge, is a complex of bridges spanning San Francisco Bay in California. As part of Interstate 80 and the direct road between San Francisco and Oakland, it carries about 260,000 vehicles a day on its two decks. It includes one of the longest bridge spans in the United States.
The toll bridge was conceived as early as the California gold rush days, with "Emperor" Joshua Norton famously advocating for it around 1855-60, but construction did not begin until 1933. Designed by Charles H. Purcell, and built by American Bridge Company, it opened on Thursday, November 12, 1936, six months before the Golden Gate Bridge. It originally carried automobile traffic on its upper deck, with trucks, cars, buses and commuter trains on the lower, but after the Key System abandoned its rail service on April 20, 1958, the lower deck was converted to all-road traffic as well. On October 12, 1963, traffic was reconfigured to one way traffic on each deck, westbound on the upper deck, and eastbound on the lower deck, with trucks and buses also allowed on the upper deck. In 1986, the bridge was unofficially dedicated to former California governor James Rolph.
