In 1881, businessman James Eddy was struck by inspiration. Northern Arizona was connected to the rest of the country by transcontinental railways and was dense with ponderosa pine forests and a burgeoning timber industry. Southern Arizona, meanwhile, was even more populated, and the isolated mining boomtowns in the deserts were home to some of the richest silver and copper veins in the world. If he could connect the south to the railroad network in the north, he would stand to make a fortune.

The benefit of connecting the two halves of the state would be twofold: sending much-needed lumber and supplies to the communities in the south, and freighting mined minerals back north where they could more easily be shipped to the industrial centers on the coasts. Only one thing stood in the way of Eddy’s plan: the Mogollon Rim.

The southern boundary of the Colorado Plateau, an elevated region that crosses into four states, is the Mogollon Rim, a massive ridge of steep slopes that cross much of Arizona. When Eddy formed the Arizona Mineral Belt Railroad company, his engineers calculated that to run a railway across the Mogollon Rim at a gentle enough grade for trains he would need to create a tunnel 3,100 feet long and 16 feet wide.

In 1883, work on the tunnel began. Over 40 men spent all summer blasting a passage through the rock. Only 70 feet of the tunnel had been completed, however, when the company ran out of funds and the work came to a halt. Eddy spent the next several years finding investors and hyping the railroad project, managing to get another 35 miles of track laid when the money ran dry and the work stopped again, this time for good.

Over the subsequent years, the 35 miles of track south of Flagstaff were torn up by locals who reused the scrap. Today, the only remaining evidence of Eddy’s ambitious but failed project is the partially completed tunnel deep in the Tonto National Forest. Other than some graffiti near the entrance, it still looks more or less exactly as it did when the Arizona Mineral Belt crews left it in 1883. The crumbling structure to the right of the tunnel entrance is the remains of the powder house where the workers stored their explosives while blasting through the ridge.