The stretch of Interstate 90 in the state of Washington is unique in the Interstate Highway system in the US, in that it is a designated National Scenic Byway. The Mountains to Sound Greenway trust has acted to protect the route of I-90 from Seattle at the Puget Sound to Ellensburg, which is the portion of I-90 through the Cascade Mountain Range. Many scenic and unique places in the Cascades can be easily accessed from the Seattle through the I-90 and its branch roads. For example, Snoqualmie Pass is only a one hour drive from downtown Seattle (weather permitting). The Greenway has seen extensive human activity for the past 200 years. Logging has occurred throughout the region since the 1880s and a major lumber mill operated in the town of Snoqualmie from 1917 to 2003. Coal mining became a major industry east of the mountains in Roslyn and Cle Elum and the Alaska's gold run in 1897 poured Seattle full of adventurers looking for supplies before heading north. East of the mountains, Native Americans, part of the Yakima Tribe used to grow native crops. Once white settlers came, they displaced the native people and began growing their own crops and well as creating cattle ranches. The Snoqualmie Valley used to be well known for its crops of hops in the 1880s and is still considered to be very fertile land. Trails have existed over Snoqualmie Pass for centuries, but it was not until I-90 was built that crossing the pass was relatively easy. Every year millions of vehicles go over the pass and allow for simple transportation across the country from the West to East Coast. By and large, the Mountain and Sound Greenway is best traveled in any season other than winter. You may not wish to climb mountains on winter and early spring, the trails are treacherous, slippery, snowy and often stormy like the rest of western Washington. Summer is the best time to do this itinerary, even then the chance of rain at the Cascades is higher than in the lowlands. Take cover in case of rain, and crouch to safety during a thunderstorm. To visit the Washington State Parks, you must purchase a Discover Pass for $10 per day, $30 per year, $10/car/day. It is possible to get it for free if you volunteer for 24 hours of any combination of state parks or fish & wildlife lands. A pass is also required for US Forest Service Trailheads for $5/car/day, $30 per year for lands at Washington & Oregon, $80 per year for the whole country. I-90 is the main corridor through the Greenway. Seattle is accessible from air through Seattle-Tacoma International Airport, from sea through the many harbors at the waterfront, depending on what ship were you on. Interstate 90 begins from next to Safeco Field. Make sure you have tire chains and basic emergency travel supplies in winter! I-90 is often closed during storms, and has even experienced landslides in the last few years! The westbound lanes from the Pass down about 3 miles are on elevated roadway that ices over easily. As stated above, I-90 is the main thoroughfare through the Mountains to Sound Greenway, but there are lots of activities to do along the way. There are a number of hiking, camping, fishing, and skiing sites found throughout. - Skiing and Snowboarding If planning to snowboard bring the proper clothing as it gets quite cold during the winter. Also a helmet is very highly recommended. Do not go backcountry skiing unless you understand the risks and are a experienced skier or snowboarder.- Hiking Follow basic safety tips if planning to go hiking. Many people every year go off trails and get lost. Follow the guide, pack for a week of hiking, to be well prepared for serious hiking adventures. People every year get injured or killed performing activities in the Greenway. Following basic safety tips and common sense for activities will make sure your time in the Greenway is a pleasant one.I-90 is also the main corridor leaving the Greenway. There are also chartered buses that go in between Seattle and Snoqualmie Pass at times, usually to access the Summit at Snoqualmie during the winter.