Final answer:
The UNESCO World Heritage Site located in the United States is Grand Canyon National Park, known for its extensive geologic history and iconic landscapes. Yellowstone National Park in the U.S. is also a UNESCO site celebrated for its natural features.
Step-by-step explanation:
The North American UNESCO World Heritage Site located in the United States is Grand Canyon National Park. This park preserves a significant geologic landscape with resources ranging from 1,840 to 270 million years old, providing insight into the Earth's geologic eras and diverse fossil records. The Grand Canyon, which is the result of erosion by the Colorado River, is one of the most studied geologic landscapes in the world.
Meanwhile, Chichen Itza is located in Mexico, which is part of North America, but not within the United States. The Great Barrier Reef is located in Australia and is not part of North America. Yellowstone National Park, which is also a UNESCO World Heritage Site, is located in the United States and known for its geothermal features and wildlife.