A journey across a Cascade mountain pass is a road trip through history

This photo of the "Sunset Highway" over Snoqualmie Pass is estimated to be from 1917. (Washington State DOT)

If you're heading over the Cascades for warm weather or mountain majesty this summer, take a moment to think about the vision, engineering skill and sweat it took to turn what were once Native American footpaths and pioneer wagon trails into the ribbons of asphalt that we navigate at 70 mph.

White, Snoqualmie and Stevens passes and the North Cascades Highway are the roadways that make it possible to travel east-west through high, rugged, nearly inaccessible places. Here's a brief history of the passes, compiled from information from the Washington State Department of Transportation archives and staff.

Background
Washington state appropriated its first funds to explore a highway route through the Cascades in 1895. Before that, any route was a rutted wagon road. In 1916, the National Association of Highways published a comprehensive U.S. map of the "Pioneer Highway," showing its course and the other major roads connected to it.

One arm of the Pioneer Highway terminated in Olympia, another in Tacoma. A spur route ended in Seattle. It eventually gave shape to some of our modern-day passes over the Cascades. The 1916 map shows two highways that crossed the Cascades north of the Columbia River Gorge: the approximations of White Pass and Snoqualmie Pass.

White Pass
White Pass Scenic Byway, or Highway 12, is the southernmost pass in the state. It winds its way between Mount Rainier, Mount St. Helens and Mount Adams, and climbs to 4,500 feet as it slices through the Cascades, descending with a panoramic vista into the Yakima Valley.

While part of this route was on the 1916 Pioneer Highway map, the modern Highway 12 through White Pass didn't officially open until 1951.

This photo of a show shed under construction on Snoqualmie Pass is estimated to be from the 1930s or 1940s. (Washington State DOT)

Snoqualmie Pass
Farther north, the Cascades' lowest-elevation pass, Snoqualmie, peaks at 3,022 feet. As with White Pass, it was also a significant early east-west route. The first wagon road, which, in places, runs near today's I-90, was completed in 1867. Ruts from pioneer wagon wheels are still visible near Denny Creek Campground.

In 1905, the first automobile made it over the pass. U.S. Route 10, the "Sunset Highway," opened to traffic in 1915. In the 1950s and '60s, when the numbered Interstate Highway System was created, Route 10 became I-90.

Stevens Pass
North of Snoqualmie Pass, Stevens Pass Greenway Scenic Byway on Highway 2 is a breathtaking route across the Cascades. A two-lane highway for much of its distance, it summits at 4,061 feet.

The original road was laid so workers building the railway across the pass had access to the construction site. It wasn't developed as a highway until 1931, when it opened as Stevens Highway, or State Road 15. Today, it's the southernmost stretch of the Cascades Loop Scenic Highway.

North Cascades Highway
The most recent and remote addition to the state's Cascade passes is the North Cascades Highway. Early pioneer roads wound their way up the east and west sides of the mountains, but didn't connect because of rough terrain and unforgiving winters.

In 1968, President Lyndon B. Johnson created North Cascades National Park. Four years later, the scenic highway across the pass opened, offering motorists a glimpse of a wild and rugged frontier previously seen by few humans. The North Cascades Highway (Highway 20), the northernmost stretch of the Cascade Loop Scenic Highway, remains one of North America's most spectacular drives.