Missouri has a lot of natural bridges. One of the largest is at Ha Ha Tonka Statte Park, spanning 60 feet and reaching more than 100 feet into the air. The tunnel through it is 70 feet long. It’s not only one of the larger ones in Missouri, it’s definitely the first one pictured. A crude woodcut of this arch appeared in The First and Second Annual Report of the Geological Survey of Missouri, G. C. Swallow, 1855.
The Natural Bridge is a showcase feature of the Ha Ha Tonka Karst Natural Area in the Missouri State Park acreage surrounding Robert M. Snyder’s once-palatial country estate. The park webpage notes: “All of these wonders (the karst features in Ha Ha Tonka park) are the result of the collapse of underground caverns in ancient geological times.”
For a sense of scale, note the four people on the slope above the arch.