Hidden under the pavement in a tight sandstone channel beside Highway 89 in Southern Utah stands a barrier of crushed vintage American cars that has remained in place for nearly sixty years. This formation is neither sculpture nor illegal dumping. It began as an actual engineering method that worked so well it was left undisturbed.

Engineers refer to this approach as riprap, a technique that places solid material along slopes or banks to limit erosion. Standard riprap uses stone or concrete blocks, yet during the 1960s highway project through Catstair Canyon, crushed cars packed with gravel served as an available substitute to hold the slope and keep sand from washing downstream. A comparable method using vehicles appeared along Nebraska's Loup River for the same purpose.

The choice made sense at the time because scrapyards held many older cars that offered little metal value. Their bulk and stackable shape made them seem comparable to rock for holding back soil. Crews filled the canyon with these compacted vehicles, covered them with earth, and built the road on top. The result stands as a distinctive reminder of the era when American highways expanded rapidly toward the interstate system.

Current condition of the Catstair Canyon site

Although the practice ended by the early 1970s, the cars stayed behind. The arid climate has kept them largely intact, and the wall looks much as it did at completion. The main change is that sixty years of traffic have pressed the vehicles into a dense layer of corroded metal, topped by a playful sign reading Trucks Enter Here.

Those who hike the short half-mile trail into the wash encounter stacks high enough to scale, revealing grilles, lamps, and panels from common 1960s American models. Two separate piles exist in the canyon, both reached from a dirt turnout past the House Rock Valley Road junction on a curve that calls for caution when stopping.

The walk involves light climbing and takes less than an hour round trip. The vehicles predate most visitors and, because they are locked into the slope, could remain long after many early highways have been replaced.