From a National Geographic online article:
Long ago bypassed by an interstate, the skinny, two-lane Historic Columbia River Highway has seen little change since its completion in 1922 as the United States’ first planned scenic roadway. The route winds above Oregon’s Columbia River Gorge, taking in six state parks, seven waterfalls, and—on clear days—views of five mountain peaks, including Mount St. Helens. Breathtaking in any season, the highway is especially picturesque in spring, when endemic wildflowers bloom, and winter, when waterfalls freeze and massive icicles hang from graceful arched bridges.
Travel tip: At Crown Point, drivers stop at the Vista House, an elegant art nouveau observatory 733 feet above the Columbia River.