Why is Hades's underworld located in the United States, why is it's location fitting for the land of the dead?

LOL!!! Because the United States probably has the highest percentage of ignorant Christians and Christian fundamentalists who think that every one who doesn't immediately join their particular sect or congregation is condemned for eternity to Hell/Hades. None of them realize that the real Hell is here on Earth in this life-time. I stopped believing in a physical Hell when I was 10 years old. Hades was originally an ancient Greek concept, although the Chinese might have had something similar at the same time. I'm not as familiar with Chinese and East Asia history and culture as I should be.