The first issue is that this is not a major bridge. Rather, it is a small fragile looking one-lane bridge that just happens to be in a very scenic location. The second issue is that the bridge serves no real purpose. There is nothing on the other side, and there are easy grade level river crossings a few miles in each direction. Finally, the bridge was not built to serve transportation needs, rather, it was built as a tourist attraction to be part of a theme park. Despite my misgivings, over 500,000 people visit the Royal Gorge Bridge every year.
The bridge is located in a unique spot. The Arkansas River flows through central Colorado. A bulge in the earth was pushed up a few miles west of Pueblo, Colorado. The river responded by cutting a gorge through that bulge. The bulge eventually reached 1200 feet above the river level. The bridge crosses this gorge. The river is just over 1000 below the bridge deck, making this the tallest suspension bridge in the world.
What makes the bridge serve no real purpose is that it sits on top of this bulge. The river can be crossed at either end of the bulge, a matter of only a few miles in each direction. Once you cross the river at a normal elevation level, you can drive around the back side of the bulge, or drive up onto the bulge in a number of locations. As a result, the bridge did not solve a transportation or access problem. It was built strictly as a tourist attraction.
Update—the Bridge Hunter web site has reported that many of the statistics for the Royal Gorge Bridge appear to be incorrect. The bridge is commonly listed as being 1,053 feet above the river, but bridge hunter Eric Sakowski measured it at 955 feet. It appears that the 1,053 number is measured from the top of the towers, which is not a common way to specify bridge height. The span length has been given as 880 feet, but Sakowski measured it at 938 feet using a laser rangefinder. The bridge is advertised as the highest bridge in the world. It may have been at one time, but today, Sakowski lists it as being the 11th highest bridge.