The U.S.A. are actually a federation of more than 50 states. While they are politically one huge country, the states differ in many things, like weather, geology, people, and even time zone. There are "cave states", which are states with many caves, especially Missouri calls itself the cave state, with 7,300  surveyed caves. Kentucky, Tennessee, and Missouri are the States with the largest amount of caves in the United States. Other say the TAG area (Tennessee, Arkansas, Georgia) is the cave-richest area of the U.S.A.. And then there is the Ozark-Plateau or Ozark Mountains, which are located mostly in southern Missouri and northern Arkansas. The Mesozoic sedimentary rocks contain many layers of limestone and many caves.
There are several things which are quite unique in the U.S.A., and the first we want to mention is the National Park system. This are parks which are owned by the government and protected by law. They are financed by public funding and by nominal entrance fees. While visitors are allowed, almost encouraged, the primary objective is the protection of nature. The parks are maintained by park rangers with funny uniforms, and as they are paid by the American taxpayer, all books and pictures they produce at work are in the public domain. The idea is that you can not made to pay what you already have paid.
The next thing is, that they had to learn the term show cave, as in showing a cave to people, making the visitors learn. They only had the term commercial cave, which means earning money from the cave. In other words, most caves are seen as venues, not as educational institution. However, the famous Gurnee's, a couple who wrote the so far only book on commercial show caves, changed this. They introduced the term in the 1980s and by simply using it made it popular.
The huge country has many natural resources, many mines for mining them, and a vast amount of abandoned mines. There are numerous show mines in the country, which are similar to show mines ion most other countries. If you are lucky there is a mining train which brings you inside, then there is an underground tour with machinery and tools, and sometimes it's possible to see the actual ore vein or seam. So show mines are actually the same as in most countries.
There are numerous and quite different subterranea in the U.S.A.. Something which seems to be rather common but is rare in other countries are abandoned underground levels of cities. Several cities were "lifted" from the ground florr to the second floor, the ground floor was covered by a new road and forgotten. And so there is now a complete abandoned city with roads, crossings, shops and public buildings right below the ground.