The Columbia River Gorge is the lowest-elevation route to get across the Cascade Mountains. Settlers following the Oregon Trail rafted down the river from The Dalles. It was dangerous, expensive too. Interstate 84 transports modern-day emigrants the eighty-some miles from The Dalles to Portland in about an hour and a half. (Of course, some modern-day émigrés do it in less time.)
After the days of rafting and before the the modern interstate, the Columbia River 
Highway carried travelers between the two cities. The first planned scenic highway in the United States, it was constructed between 1913 and 1922. Attorney/entrepreneur Sam Hill and engineer Samuel Lancaster promoted the new roadway as a “destination unto itself.” Their design put scenery before commercial traffic. Rather than following the most direct path, the route meandered so not to miss scenic waterfalls or panoramic vistas.
With the establishment of the U.S. highway system in 1926 the route became part of U.S. Highway 30. Before construction was finished at the eastern end, the highway was deemed obsolete. Motorists wanted to get to their destinations more than they wanted to admire the scenery. Flooding resulting from the new Bonneville Dam necessitated realignment of some sections. Lancaster proposed a new river-level route, while keeping the now-old road as a scenic highway.
The road officially became the Historic Columbia River Highway with the State of Oregon responsible for maintenance. Interstate 80N, later relabeled I-84, begins in Portland and follows the Columbia River Gorge along the Oregon side. It meets up with I-80, originating in San Francisco, at Salt Lake City.
If you plan to travel the historic route, I recommend a cold, wet day. On sunny, warm days you will find a crowd at the Crown Point Vista House. At Multnomah Falls, you will likely encounter gridlock on the highway and a very slim chance you will find a parking space.
Addendum Sam Hill’s other projects include the Peace Arch at the Washington-British Columbia border, Maryhill Museum on the Washington side of the Columbia and a Stonehenge replica at Maryhill. Samuel Lancaster engineered Lake Washington Boulevard in Seattle among other accomplishments.
