Yes, the United States who have been founded, but it might have been harder to do. If the question implies that the Europeans did not even explore the Americas, the results would be drastically different than if the Europeans just said hi to the Native Americans and traded with them.
Someone was bound to find America other than the Europeans and colonize it. It would obviously be extremely different than what happened in reality, but it would happen. On another note, there would probably be a difference in the ways the other colonizers(?) interacted with the Native Americans, maybe the other colony would become a part of the Native American society and they would become one new sort of nation.
If we weren't colonized by Europeans someone else would defeat the native American. For all we know without the Europeans colonizing might have done, we might have had a war of independence against China, Vietnam or maybe even Israel(probably not). The world would have likely just have made something to send a man on the moon. The axis powers might have conquered the world if we were founded by Native Americans or conquered by The Soviet Union.
The Native Americans would have never made anything that would be remotely like the America that we know today. Now that is not to say that they could not have made a country in North America. However, many Native Americans did not want the Europeans in America and their beliefs and tradition would not have resulted in anything like the US. Do remember that a lot of the ideas that America was founded on came from earlier European philosophers. For example, the idea of life, liberty, and the pursuit of happiness came from John Locke and English philosopher who lived between 1632-1704.
The Natives didn't believe in the concept of owning land, but they did have a notion of areas you could and couldn't go because of the likelihood of running into a hostile tribe. They had been in America for an extremely long time, but never established the entire land mass as it's own entity. Native American is sort of a catch-all term for all of the natives, but there were many many tribes throughout the whole region who very often fought each other. They had many independent tribe nations, but the idea that they would have united as one great nation is pretty unrealistic. Especially given the fact that it never happened.