Waterfalls usually occur when a stream of water gets interrupted somehow. This typically happens when the stream of water passes over a layer of some form of rock. Waterfalls are often used by some cities in the United States as a form of energy. The highest waterfall in the world is located Venezuela. Angel Falls' waterfall is 3,230 feet tall. The tallest waterfall in the United States is Yosemite Falls, which is located in Yosemite Park in California.