Timberline Trail
Timberline Trail (Forest Service trail #600) is a long, multi-day loop that circumnavigates Mount Hood in Oregon, largely staying at or near treeline. The route is constructed to run through Mount Hood Wilderness and alternates through glacial-fed drainages, with many river/stream crossings that can make the trip feel more demanding than the average mileage suggests.
Plan on about 67.95 km (roughly 40–41 miles) for the full loop; most hikers complete it in 3 to 4 days. The trail is typically most workable in summer through early fall, with common hiking season running from mid-July through early October (late July to early October is also often cited).
The hardest recurring challenge is the fast-moving fords of glacial-fed water. Newton, Coe, Muddy Fork, Sandy, and White Rivers/creeks are typically the most challenging crossings on the loop, and conditions can change quickly with time of day, weather, and melt—shaping when you should tackle each ford.
A notable overlap section runs between Timberline Lodge and Yocum Ridge, where the Timberline Trail follows the Pacific Crest Trail #2000 for a stretch. North-side canyon travel generally involves later snowmelt, while multiple zigzags and canyon descents on the loop put you repeatedly in and out of glacial drainages.
For planning camps and logistics, there are multiple access points around the mountain, but Timberline Lodge is a common anchor for starting/finishing the loop. The trail is associated with the Mt. Hood National Forest management area; backpacking camping occurs at multiple informal sites, with specific restrictions around sensitive areas and near water bodies.
The trail was constructed in the 1930s by the Civilian Conservation Corps, and it has seen reroutes over time due to washouts and landslides. Some sections can be affected by washouts and blowdown, so be ready for variable footing and rerouting needs as conditions change from year to year.
More information: Visitor information, Wikipedia, Timberline Trail (Mt. Hood Circumnavigation)