Mountains to Sound Greenway is in west-central Washington. It follows I-90 between Eastgate, which is just east of Seattle, and Ellensburg. The byway is about 100 miles long and remains open year-round. Use of chains or snow tires are generally required in winter over Snoqualmie Pass.

Mountains to Sound Greenway takes the traveler from Puget Sound to the forested mountains of Wenatchee and Snoqualmie National Forests. It crosses 3,022-foot Snoqualmie Pass, travels alongside beautiful mountain lakes, and provides access to abundant outdoor recreation possibilities. Although it follows the Interstate, several exits provide access to the national forests and opportunities for camping, picnicking, fishing, and hiking.

There are three national forest campgrounds and one state park located a short distance off the byway. Tinkham, Denny Creek, and Crystal Springs are national forest campgrounds. They are generally open May through September and have an RV length limit of 22 feet. Hookups are not provided at any of the national forest campgrounds. Tinkham has 48 RV and tent sites; Denny Creek has 33; Crystal Springs has 25 sites. Lake Easton State Park is near the town of Easton. It has 45 campsites with complete hookups and 92 without. The park provides access to nearly 40 miles of trails for hiking, backpacking, and cross-country skiing in winter.

Alpine Lakes Wilderness Area lies north of the byway. It preserves 394,000 acres of Cascade Mountain wilderness and contains nearly 700 small mountain lakes. Hikers and backpackers will find over 600 miles of trails running through the area, including the Pacific Crest National Scenic Trail. Byway travelers can exit I-90 at either Exit #80 or Exit #84 and travel north through Roslyn to the road's end at the wilderness boundary. Numerous national forest campgrounds are located along this side trip, which follows Cle Elum Valley Road.

Information: Washington Department of Trade and Economic Development, 360-753-5601. Wenatchee National Forest, Cle Elum Ranger District, 803 W 2nd St, Cle Elum WA 98922 / 509-674-4411. Snoqualmie National Forest, North Bend Ranger District, 42404 SE North Bend Way, North Bend WA 98045 / 425-888-1421. Washington State Parks & Recreation Commission, Information Center: 800-233-0321