Zion-Mt. Carmel Tunnel: Engineering a New Kind of Tourist

Before nineteen thirty, you could only get into Zion Canyon from the south. The canyon walls closed off every other approach. Visitors arrived, turned around, and left the same way they came. The landscape that would become the defining scenic loop of the American Southwest was effectively a dead end.

The Zion-Mount Carmel Highway, completed in nineteen thirty, changed that. Its centerpiece is a one-point-one-mile tunnel bored through solid Navajo sandstone at the canyon's eastern wall, at the time one of the longest road tunnels in the United States. The engineering required blasting a series of gallery windows in the cliff face so workers could remove debris and so light could enter. Those windows, which you pass through as openings in the tunnel wall, are still the only place in the canyon where you can see the vertical drop below while in a vehicle.

The tunnel connected Zion to the east entrance and from there to the road to Bryce Canyon. That connection was not accidental: it was the infrastructure decision that made the Mighty Five loop possible, turning what had been a collection of separate difficult destinations into a circuit that a visitor with a car and a week could plausibly complete. The National Park Service and the Bureau of Public Roads built it in partnership; the Union Pacific Railroad's Utah Parks Company lobbied hard for the route because it would sell Pullman tickets from both ends.

The tunnel is listed on the National Register of Historic Places. Large vehicles, including most recreational vehicles and oversize trucks, require a one-way escort through it and pay a fee. The canyon walls on both sides of the portal are the same unbroken sandstone the workers drilled and blasted through ninety-some years ago.