Historic Columbia River Highway State Trail will stretch 73 mi. from Troutdale to The Dalles when completed. Currently 65 miles of the scenic recreation trail are finished and open to bicyclists. Portions follow the Historic Columbia River Highway and, temporarily, I-84, while other parts are closed entirely to motorized traffic and are open to pedestrians and wheelchair users, including the Bonneville and Twin Tunnels segments.
The Bonneville Segment connects John B. Yeon State Scenic Corridor and Bridge of the Gods in Cascade Locks. At either end of the Twin Tunnels Segment, which is more than 4 miles long, are visitor centers and trailheads, both named for Sen. Mark O. Hatfield. The Mosier Twin Tunnels, for which this section was named, are original highway tunnels constructed in 1921 and restored in 2004. Visitors can see graffiti left behind by drivers stuck in the tunnels during a November 1921 snowstorm and tunnel windows offering views of the gorge below.