Siskiyou Summit, Mountain pass on Interstate 5 in Oregon, United States

Siskiyou Summit is the 4,310-foot (1,310 m) high point of Interstate 5, about 4 miles (6.4 km) north of the California border in the Siskiyou Mountains. Rebuilding the highway on its current alignment cut the summit down by 49 feet (15 m). It lies 0.5 miles (0.8 km) east of the historical Siskiyou Pass, a separate nearby pass.

The pass was first crossed by Europeans in 1827 when Peter Skene Ogden of the Hudson's Bay Company traveled through the area during fur trading expeditions. The route later became an important trading corridor before developing into the modern interstate highway in the 20th century.

The Pacific Crest National Scenic Trail crosses Interstate 5 at Siskiyou Summit on its 2,650-mile route between Canada and Mexico. Hikers walking the Oregon section pass this point about 12 miles south of Ashland, where the trail meets the highway near the 4,310-foot high point.

The pass requires special caution during winter months from November through April, when snowfall and freezing temperatures frequently occur. Travelers should check weather conditions before driving through and be prepared for sudden changes in road conditions.

The road features a steep grade that extends for several miles, requiring truck drivers to use special braking procedures and techniques. This demanding section requires regular brake system maintenance and constant speed control.