In its thinnest section the arch is only 6 feet thick, yet it supports a span of rock 290 feet long (see article on the Dimensions of Landscape Arch). Indeed, this arch could collapse at any time: any day, any year, any decade, or any century.

On September 1, 1991, a 73-foot slab of rock fell out from underneath the thinnest section of the span. This was captured on video by a Swiss tourist who happened to be behind the arch at the time. On the sound track of the video, another hiker can be heard saying "I don't think I want to walk back under there!" The rock that fell, however, was probably not structurally important to the arch. In fact, by reducing the weight of suspended rock, the arch was probably strengthened.

On June 5, 1995, a 47-foot mass of rock fell from the front of the thinnest section of the arch, followed by another 30-foot rock fall on June 21. Due to these events the Park Service has closed the loop trail that once led underneath the arch.