U.S. Route 71 (US 71), once classified as "one of the most dangerous highways in America",[citation needed] includes a perilous stretch between Alma and Fayetteville through the Ozark Plateau.

Approved in 1987 and completed in 1999, at a cost of $458 million, the alternate route, I-540, eventually renamed I-49,[2] had an obstacle of an unnamed 1,800-foot-tall (550 m) peak just north of the Washington—Crawford county line, in what John Haman of Arkansas Business called "smack in the middle of motoring wilderness.

The alternative would disfigure the topography and necessitate a 200-foot (61 m) cut creating 8 million cubic yards (6.1×10^6 m3) of debris to be disposed, as it was not usable within the project.

At an elevation of 1,640 feet (500 m) above sea level, twin parallel tunnels were mined, not bored, through the mountain in a horseshoe contour, since a circular shape, like that used in sewer or train projects, was not needed.

Blasting, drilling, and excavation removed native shale and sandstone rocks, slowly chipping to the desired width and length.