Try to imagine traveling around a place like Europe... really, all over Europe. Think about how much diversity there is there in culture, appearance, topography, nature (plant life, etc), attitudes, and language, and how much area you would have to cover to see all of it. You woud have a very similar experience traveling around the US except that there would be fewer language differences (although there would still be differences, both in languages as well as in dialects), and also, while the amount of diversity would be similar, the actual attributes, themselves, would be different.