Iron Horse State Park (509/656-2230, www.parks.wa.gov ) is Washington’s most unusual state park, a 113-mile long trail that starts near North Bend , crosses the Cascades, and continues all the way to the Columbia River. A centerpiece of the state’s rails-to-trails program, the park is open to hikers, skiers, mountain bikers, and horseback riders but closed to motorized vehicles.
The trail begins at Olallie State Park  (I-90 Exit 34), climbs up the west slope of the Cascades to Snoqualmie Pass , and then descends past Cle Elum  and Ellensburg  (there is a short gap near here) before ending near Vantage along the Columbia River.
The gravel trail is gentle, with a maximum 2 percent grade. It crosses 30 substantial trestles and goes through four tunnels, including the 2.3-mile Snoqualmie Pass tunnel; bring flashlights and warm clothes.
No overnight camping is allowed. Trailhead access points can be found near many I-90 exits along the way, including Olallie State Park, Snoqualmie Pass, Easton, South Cle Elum, and Thorp.