Along the East Bay shoreline, bridges, oil refineries, factories, and ports reflect a commercial history dating back to the Gold Rush. The Carquinez Strait provided easy passage for ships carrying cargo and people to and from the gold fields and Central Valley. Its distance from population center, combined with access to deepwater ports, made it an advantageous industrial location. At one time, the view included another oil refinery, a black powder factory, and a lead, silver, and gold smelter with the world's tallest smokestack. The Al Zampa Memorial Bridge, completed in 2003, is the third bridge to span the mouth of the Carquinez Strait. These bridges were designed for trucks and automobiles to traverse the waterway, and another bridge near Benecia allows trains to cross the strait. Ships, barges, tugs, and ferries continue to play an important role in moving people, oil, cars, agricultural products, and hundreds of other commodities across California.