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The Journal · One Park, Done Right

The Longest Arch
Is Also the
Thinnest

By Jordan Hogenson · Published Sep 12, 2026 · Arches National Park, Utah · What happened when visitors watched a piece of it fall
Photo: NPS / Public Domain · Sandstone fins, Devils Garden

At about 2:45 in the afternoon on September 1, 1991, a group of visitors stood beneath Landscape Arch in Devils Garden and watched a slab of sandstone break away from its underside and fall. Royce Morrison had a camera. Michael Müller had a video recorder. Between them, they caught one of the only documented natural arch collapses ever witnessed in real time by the public.

Nobody was hurt. But the trail that had run directly beneath the arch for decades closed that day and has never reopened, and the reason has everything to do with what makes Landscape Arch remarkable in the first place: it's the longest arch in North America, and also, in places, dangerously thin.

01Stop One · The Afternoon It Fell

Witnessed, Photographed, Filmed

Most arch collapses happen with no one around. This one happened in front of a crowd, on camera.

The rockfall at Landscape Arch on September 1, 1991, is one of the best-documented natural arch failures anywhere, precisely because it happened in front of people rather than in the middle of the night. A single large slab separated from the arch's underside and fell to the wash below while visitors watched. The National Park Service's own account of the day names both Morrison and Müller as the visitors whose photographs and video preserved the moment. More rock came down from the arch again in the years that followed, and the ground beneath it has been closed to hikers ever since, for a reason that's easy to understand once you look up: there is no way to predict which piece of a fin like this one goes next.

02Stop Two · A Record by 88 Meters

The Longest Arch on the Continent

Landscape Arch spans 290 feet, a length that makes it the longest natural arch in North America and the fifth-longest known anywhere on Earth.
Desert rock formations, Arches National Park
NPS / Public Domain · Desert rock formations, Arches National Park

Landscape Arch measures 290 feet across, a span long enough to make it the longest natural arch anywhere in North America. Globally, the Natural Arch and Bridge Society ranks it fifth, behind four arches in China. Named during the same 1933-34 Beckwith expedition that renamed Delicate Arch, Landscape Arch sits in the Devils Garden area at the park's northern end, reached by a mostly flat, 0.8-mile graded gravel trail that remains open even though the ground directly under the arch does not.

From National Parks Hub

Plan the Devils Garden Trail

Landscape Arch is an easy first stop on the Devils Garden trail system. The trip planner maps the full loop, including which arches you can still walk beneath.

Open the Trip Planner
03Stop Three · Eighteen Feet Wide

Long, Tall, and Barely There

At 77.5 feet at its highest point but only 18 feet wide in cross-section, Landscape Arch is shaped less like a doorway and more like a ribbon stretched almost to its limit.

Most arches people picture are roughly as thick as they are tall, a stone doorway with real bulk to it. Landscape Arch isn't built that way. It rises 77.5 feet at its highest point but narrows to just 18 feet across at its thinnest cross-section, a ratio that makes it look, from below, less like an arch and more like a thin stone rainbow that shouldn't still be standing. That geometry is exactly why the 1991 collapse wasn't a surprise to park geologists, even if the timing was: a span this long, held up by rock this thin, was always going to keep shedding pieces of itself.

Landscape Arch, at a Glance
  • Span 290 FT
  • Height 77.5 FT
  • Thinnest width 18 FT
  • Major rockfall SEP 1, 1991
04Stop Four · What Changed After

The Trail That Never Reopened

Not every arch failure at Arches National Park has come with a warning, or a witness.

The area beneath Landscape Arch has stayed closed to hiking since 1991, and it's a decision that's aged well. Elsewhere in the park, Wall Arch, once ranked twelfth-largest among the park's more than 2,000 named arches, collapsed sometime between the night of August 4 and the morning of August 5, 2008, with no witnesses at all. Park staff later noted stress fractures in what remained of the formation, the same kind of internal weakening that had been visible in Landscape Arch's exposed underside for years before 1991. One collapse happened in daylight, photographed by strangers. The other happened in the dark, unseen. Landscape Arch is still standing, longer than any other arch on the continent, and the same slow physics that already took a piece of it once hasn't stopped.

•Sourcing

Facts and figures checked against NPS.gov's account of the 1991 Landscape Arch rock fall and its Wall Arch collapse records, and the Natural Arch and Bridge Society's published arch-length rankings.

Royce Morrison's photographs and Michael Müller's video footage from that September afternoon are still the closest thing anyone has to watching an arch die in real time. What they caught wasn't the end of Landscape Arch, just proof of what was always going to happen eventually to a 290-foot span of stone barely 18 feet wide at its narrowest point. The arch is still there. So, somewhere in that rock, is whatever comes down next.