East Longs Peak Trail – Longs Peak Trail – Keyhole Route – Shelf Trail, National Historic hiking trail in Rocky Mountain National Park, Colorado.

This is a historic hiking trail in the Rocky Mountains leading to the summit of Longs Peak at over 14,000 feet (4,270 m). The route winds through forests, alpine meadows, and rocky sections, with the Keyhole portion featuring narrow ledges and steep rock faces.

Reverend Elkanah Lamb laid out the trail in 1878, before the area became parkland. Enos Mills extended it in 1910. It was listed on the National Register of Historic Places on 10 July 2007 for its role in the park's early recreational development.

The trail's names mark its history: the Keyhole Route takes its name from the notch in Longs Peak's ridge that hikers pass through, and the Agnes Vaille Shelter near the route honours a climber who died on the mountain in 1925. Reverend Elkanah Lamb, who laid out the trail in 1878, also guided early parties to the summit.

The climb requires preparation for high altitude, changing weather, and technical sections with steep rocks. Sturdy footwear, plenty of water, and experience with mountain hiking are essential for safe travel.

The trail was listed on the National Register of Historic Places on 10 July 2007, cited for its role in the early recreational development of what became Rocky Mountain National Park. It was laid out in 1878 by Reverend Elkanah Lamb, decades before the area was designated parkland.