Interstate 90 has a secret: 1.5 million acres of forest right off the exit

Seattle’s back door to the Cascades

You can leave downtown Seattle on Interstate 90 and hit real wilderness in under an hour.

The Mountains to Sound Greenway follows that highway for nearly 100 miles, from Puget Sound east to Ellensburg, climbing over Snoqualmie Pass and dropping into the dry country on the other side.

Along the way, you pass 1.5 million acres of forest, rivers, farms and mountains.

The corridor packs waterfalls, alpine lakes, old mining towns and a two-mile railroad tunnel into a single drive, and most of it sits on public land.

Ice and ancient footpaths built this route

Glaciers and volcanoes carved this corridor long before anyone laid asphalt.

Native peoples crossed the Cascades here on foot, following trails to fish and trade on both sides of the range.

Old wagon routes and rail lines later traced those same paths, and the roads you drive today still follow their lead. In 2019, the Greenway earned National Heritage Area status.

Interstate 90 itself was the first interstate ever named a National Scenic Byway, a fact most drivers blow right past at 70 mph.

Snoqualmie Falls drops 270 feet into mist

About 30 miles east of Seattle, the Snoqualmie River steps off a cliff and falls roughly 270 feet, taller than Niagara.

You can watch from an upper deck at the rim or take the trail down to a lower platform closer to the spray. When the river runs full, mist rises high above the pool and drifts across the viewing area.

In the evening, lights hit the cascade after dark, and the whole scene changes. It sits right off I-90, so there is no excuse to skip it.

The Snoqualmie Tribe’s sacred waterfall

The Snoqualmie Tribe has honored this place for generations.

Tribal tradition holds that Moon the Transformer created the falls from a fish trap, and the site remains central to their cultural identity.

A lodge first built above the falls in 1916 is now Tribe-owned.

In 2019, the Tribe purchased the falls and 45 surrounding acres for $125 million, protecting the sacred grounds from planned development.

That purchase put one of Washington’s most visited landmarks back in the hands of the people who have always called it sacred.

A power plant carved inside the rock

Below the falls, engineers did something nobody had tried before.

In 1899, they opened a power plant 270 feet underground, built entirely inside the rock at the base of the cascade.

It was the world’s first completely underground power plant, and it drew energy straight from the river above. A second plant went in downstream in 1910 and later grew larger.

Both still run today, feeding a small share of the region’s electricity from the same water that draws the crowds up top.

Rattlesnake Ledge earns its crowd

The hike runs about four miles round trip from Rattlesnake Lake near North Bend, and you climb roughly 1,160 feet through shaded forest to reach a rocky ledge at the top.

It is one of the most visited trails in King County, and when you see the view, you understand why. Mount Si fills the skyline to the north, the lake sits below like a mirror, and Cascade peaks line up behind it.

The moderate grade makes it a solid pick if you are newer to hiking.

Mount Si rises nearly 4,000 feet from the valley

If Rattlesnake Ledge feels too easy, Mount Si will fix that.

The round trip stretches about eight miles from the valley floor near North Bend, and you gain over 3,100 feet on a steep, forested climb that does not let up.

Local hikers treat it as a training ground for bigger Cascade summits.

The rocky top opens to wide views across the Snoqualmie Valley, and the peak towers nearly 4,000 feet above the town below. Your legs will remember this one.

Old-growth giants and twin waterfalls at Olallie

Olallie State Park covers about 2,500 acres of lowland forest where towering old-growth fir and cedar block most of the sunlight.

A gentle trail leads to Twin Falls, a series of drops tucked into thick woods where the sound of water stays with you the whole way. Nearby Weeks Falls adds a second cascade to the walk.

Rock walls along the river pull climbers into the area, so you may spot people scaling the stone while you hike past on the trail above.

Walk 2.3 miles through a pitch-black tunnel

The old Snoqualmie Tunnel runs 2.3 miles straight through the mountain, and it is among the longest rail-trail tunnels in the country. You step inside and the temperature drops fast.

Daylight disappears within minutes, and the passage stays cold and dark even on the hottest summer days. Bring a headlamp and warm layers because you will need both.

The tunnel sits on the Palouse to Cascades Trail, a cross-state route that follows the old railroad grade through some of the best scenery in Washington.

A rail trail that crosses the whole state

The Palouse to Cascades Trail follows that old railroad grade for over 100 miles, and its gentle, flat surface suits walkers, bikers and horseback riders alike.

The path crosses tall trestles, passes through forests and runs alongside rivers and mountain lakes.

Major trailheads sit at Rattlesnake Lake, Hyak and Cle Elum, so you can pick up the trail from several points along I-90.

The western section carries you from North Bend deep into the Cascades without a single steep climb.

Roslyn’s 24 nationalities dug coal here

Roslyn started in 1886 after coal turned up nearby, and the town grew fast. Workers arrived from at least 24 nationalities, building a patchwork community around the mines.

The last mine closed in 1963, but the town kept its bones.

Today, the Coal Mines Trail runs about 5.5 miles through Cle Elum, Roslyn and Ronald on a flat path where interpretive markers point out old mining sites along the way.

You walk the same ground those miners worked for nearly 80 years.

Granite peaks and glacier-carved lakes above the pass

The Alpine Lakes Wilderness spreads across the high country near Snoqualmie Pass, and trails climb from the highway to clear lakes sitting in glacier-carved bowls.

The Salmon La Sac area holds some of the region’s most popular day hikes, where granite peaks like Mount Stuart tower over the backcountry.

In early summer, wildflowers and beargrass bloom across the meadows, and the higher lakes still hold ice at the edges. This is where the Greenway stops feeling like a road trip and starts feeling like real backcountry.

Drive the Mountains to Sound Greenway in Washington

You can pick up the Greenway along Interstate 90 heading east from Seattle toward Ellensburg.

The Snoqualmie Pass Visitor Center is open Friday through Sunday in season, but hours change, so check ahead before you go. Many trailheads require a Discover Pass or Northwest Forest Pass.

The Snoqualmie Tunnel opens around May 1 and closes by late October because of falling ice, and you will want a headlamp and warm layers inside.

Some forest roads and park trails close for storms and washouts, so check current alerts with Washington State Parks and the Snoqualmie Ranger District before heading out. Trails range from flat family walks to steep summit climbs.

This article was created with AI assistance and human editing.

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