The Geek Atlas

Missouri

103

Gateway Arch, St. Louis, MO

38° 37′ 28.81″ N, 90° 11′ 5.82″ W

Gateway to the West

The Gateway Arch in St. Louis, Missouri, stands at 192 meters, and is the tallest monument in the U.S. (Figure 103-1). It was opened in 1967, and the view from the top is spectacular. The top is reached by riding in small five-person trams that travel up the legs of the arch to the observation deck at the top. While you’re up there, you can contemplate the perfect shape of the arch—it’s a catenary.

Figure 103-1. The Gateway Arch; courtesy of Pat Dye (gobucks2)

Even though the arch is man-made, there’s something natural-looking about it, because a catenary is a shape made simply by the force of gravity. Take a short piece of rope (or string, or a necklace of uniform thickness) and hold one end in each hand. With your hands level, the rope falls into a graceful curve under its own weight pulled down by gravity. That shape is a catenary (a term coined by Thomas Jefferson based on the Latin ...