In 1930, when the Zion Mt. Carmel Tunnel was completed in Zion National Park, it was the longest tunnel anywhere in America outside of an urban city. Today, this 1.1-mile tunnel navigates the innards of a soaring sandstone mountain, and provides a conduit connecting Zion National Park with Utah’s famous Bryce Canyon. The road itself, the Zion-Mt. Carmel Highway, is listed on the National Register of Historic Places for its beauty and feats of engineering—the grandest of which is the Zion Mt. Carmel Tunnel that’s become an attraction in itself. As a means of illuminating the deeply dark tunnel, multiple “windows” have been cut through the wall to showcase the view outside, though you’ll want to keep moving, rather than stop, to make sure traffic keeps flowing. In the three years that it took to complete the Zion Mt. Carmel Tunnel, the total cost eventually ballooned to just over half a million dollars. In 1930 that sum was unconscionable for simply creating a road, but seems like a bargain when you consider today the feat that the builders pulled off.
If your vehicle is over 11’4” (3.4m) high, or wider than 7’10” (2.4m), you will need to arrange a $15 tunnel permit for an escorted pass through the tunnel. The fee is payable at the entrance stations before you reach the tunnel, so it’s important to measure your vehicle in advance if you think it could be cutting it close. No pedestrians or bicycles are permitted at any time of year, and advance notice is required in winter from November 1-March 9th.