Glencliff is an unincorporated community within the White Mountain National Forest in the town of Warren in Grafton County, New Hampshire, United States.

The village was known as Warren Summit until an unfortunate incident in the early 1900s, when two trains crashed in a head-on collision, due to confusion over town names.

[2] Glencliff is located in a high valley (1,000 feet above sea level) known as Oliverian Notch, the westernmost pass through the White Mountains.

The Appalachian Trail passes directly through the village, with the Glencliff Post Office serving as a major resupply point for its hikers.

[citation needed] Recreational activities in the area include hiking, snowshoeing, walking, jogging, snowmobiling, and hunting.