The westward expansion during the time of Manifest Destiny, the Americans felt they needed to move westward because the growing nation needed more space for the growing population of the 13 colonies, and they needed more natural resources.
George Washingtons presidency was vital in the development of young America. Washington was a trusted figure, a war hero, he lead America to its independence during the Revolutionary war. The citizens of the united state followed him with their trust.
Washington set many of the precedents for the president that are still followed to this day, for example the two term limit was established after he retired, only to be broken by FDR and it was later instated as a law. Without George Washington America would have been extremely different.
What Treaty are you talking about?