why usa is called uncle sam

अमेरिका, जिसे संयुक्त राज्य अमेरिका (United States) भी कहा जाता है, को "अंकल सैम" के नाम से पहचाना जाता है। यह नाम देश और उसकी सरकार का प्रतीक बन गया

The United States, often referred to simply as the United States, is known as "Uncle Sam."  This nickname has become a symbol of the country and its government. The term