Okay, so imagine you're playing with sand in a big sandbox. Now, you know that if you pour water over the sand, you can make it into little sandcastles or even shape it into different things like a mountain or a river. But what if you pour the water over the sand and there's nothing left? That's what happened in the Great American Desert.
The Great American Desert is a big stretch of land in the middle of the United States. A long time ago, people thought it was too dry and too hot to grow anything, kind of like how you can't grow a garden in the sand when there's no water. But, people were wrong! They thought this way because it hadn't always been a desert.
Years ago, the Great American Desert was actually a lush landscape filled with trees, plants, and animals. But, because people who lived there didn't take care of the land, they cut down the trees, let their animals eat all the plants which led to overgrazing, and left nothing to help the soil stay healthy. This caused the land to become very dry and it couldn't support any life forms anymore.
Now, the Great American Desert is mostly empty, except for some cacti and other plants that can live in the dry conditions. People can travel through it, but it's not a place where they can easily live or grow crops.
So, just like in your sandbox, if you don't take care of the sand and keep it wet and healthy, it will eventually dry up and become a desert without any life.