The Port of Lewiston is the farthest inland port on the west coast and is Idaho's only seaport. It is 465 miles upriver from the Pacific Ocean, on the confluence of the Snake and Clearwater rivers. Lewiston is the final stop on the nation's second-largest water transportation highway. In 1958, the residents of Nez Perce County voted the port into existence. It became a working port in 1975 when the Lower Granite Dam was completed on the Snake River. The raging rivers needed to be quieted enough for barge traffic, and so there was a series of eight dams and locks built on the Columbia/Snake system. The water highway significantly reduces rail or highway shipping costs; it takes about 50 hours to get from Lewiston to Portland, Oregon by barge. Today, about one million tons of wheat and barley are exported through the Port annually. Eleven steamship lines provide containers to move an additional million tons of containerized cargo. With 40 percent of the nation's white wheat traveling through the Port of Portland, much of it passes through the Port of Lewiston on its journey to the coast. The port is served by five tug and barge lines, two U.S. highways, 10 truck lines, and a short-line railroad that connects with the Union Pacific and Burlington Northern railroads. There also are 11 major container companies represented at the Port. Several interstate trucking lines serve the area; containerized shipments relay exports to the coast, enabling the port to ship to some 40 foreign countries in eight major regions of the world.