No, Niagara Falls is not the tallest waterfall in the United States; in fact, it doesn't even crack the top 100 in terms of sheer height. While it is world-famous for its massive volume of water and its horizontal scale, the tallest drop at Niagara (Horseshoe Falls) is only about 167 to 188 feet (51 to 57 meters). For comparison, the tallest waterfall in the U.S. is generally considered to be Olo'upena Falls in Hawaii, which plunges roughly 2,953 feet (900 meters) down a remote sea cliff on the island of Molokai. On the mainland, Yosemite Falls in California is significantly taller than Niagara, with a total drop of 2,425 feet (739 meters). Niagara Falls' fame comes from its flow rate rather than its height; it is the most powerful waterfall in North America by volume, with over six million cubic feet of water falling over the crestline every minute during peak daytime hours, making it a geological marvel of power rather than vertical distance.