Because of the economic compatibility and military prowess. Also the US traded many things such as led (1.8 billion in the 1800's) this made it a world market.
The U.S assert themselves as the world's power because of the economical and military strenght of the country. Because of the highly influential role in the world's politics, the president of USA is considered as the most powerful person in the world.
Explanation:which means that they can send job- related mail without paying postage fees , members of congress receive free office space, parking and trips to there home state.
