This dam was one of the largest New Deal projects of the Depression era. Completed in 1937, it was the first major dam on the Columbia River. Dam construction brought thousands of jobs, and the cheap electricity produced by the dam promised future industrial employment. Bonneville's two hydroelectric powerhouses back up the Columbia River for 15 miles and together produce over 1 million kilowatts of power. The visitor center offers powerhouse tours at 11am, 1pm and 3pm June to September.
There are also good exhibitions and videos at the visitor center displaying the dam's history. Downstairs, underwater windows allow visitors to watch salmon (and lampreys!) swim by. From the roof you can clearly see the fish ladders, which allow migrating fish to negotiate around the dams. There's another visitor center on the Washington side.