The Bridge of the Gods at Cascade Locks is the first bridge east of Portland in the Columbia River Gorge. The Pacific Crest Trail crosses the Columbia River via this bridge. This is the site of an enormous landslide, now believed to have occurred around AD 1700. The landslide dammed the Columbia River to a height of 200 feet. The river soon carved its way through. This led to Native American legends of the "Bridge of the Gods" and a fight between two mountain gods.
The debris of the landslide created treacherous rapids in the Columbia River. Native Americans and Oregon Trail pioneers had to portage around the rapids. The Cascade Locks and Canal were completed in 1896 to provide navigation around the rapids. You can see the remnants of the locks here at Marine Park in the town of Cascade Locks. The main locks were submerged when Bonneville Dam was built in the 1930's.