The United States holds as its motto "E Pluribus Unum": Out of Many, One. This idea of the United States acting as a cultural melting pot has with it the responsibility of integrating that melting pot in the same conscious, critical, and respectable manner that was initially laid out by the Macedonian King Alexander the Great and the lay out of his empire. Alexander sought to unify and intertwine the immense cultures of his empire: the Egyptian, Greek, Persian, Babylonian, and other cultures. This dream of multiculturalism was so engraved into Alexander's mind that he personally took the effort to marry brides and adopt customary traditions of the cultures he conquered. His dream has been carried on by countless individuals from all walks of live who have learned of his ambitions and goals. Western civilization, and in particular the United States, embodies to this day many aspects of his original vision.
The United States takes great pride in its cultural heritage being derived from the great civilizations of Greece and Rome. Rome saw itself too as a cultural inheritor of the Greeks; and attempted to perfect the original Greek democratic model. Unfortunately, Rome eventually forsakened those democratic attributes and fell into imperial tendencies, just as the ancient Greeks had. We now face today a similar forsaking of that ancient Greco-Roman cultural mantle by the United States in the same imperial ventures and constructs that led to the undoing of its predecessors.
The basis of the United States as an administrative entity created a multi cultural system through the Continental Congress; which united the American States through the Articles of Confederation, which bound a formal alliance. States at that time were distinct and different, just as any other nation-state in Europe was at the time. The eventual adoption of the Constitution further refined this original connection into a stronger federation that bound the states in ways that could largely erase the border distinctions between them, and creating a common wealth of States. And in the time since the Constitution was created, the Civil War pushed the American experiment to the point of collapsing into that imperial embodiment that sent empires of the past into the dustbin of history. The slave masters and economic aristocracy of southern states advocated for the monarchical restructuring into the confederate states, and originally sought a Central/South American empire in its original foreign-policy ambitions. This divergence of the American system would've resulted in a similar breakdown of civilization as the imperial system of Rome eventually collapsed into after years of corruption and incompetence. The northern states, or the Union as it was known, retained the principle of unity as a collective of individuals unified behind common cause. This inevitably pushed for the social rearrangement towards actualizing the Democratic dream enshrined in the Constitution and conceived in the Greco-Roman world.
The dismantling of the slave apparatus and economic system; the integration of millions of people formerly considered property now considered full members of the civilization. The worker uprisings of the 1870s-1940s that united the lower classes, the Masses, behind the commonality of economic dignity and social responsibility to help one another; unifying groups previously divided by race and other superficialities. The blending of spiritualities, religions, and philosophies into a multitude of variations that unites systems around the world together through the Great Awakenings throughout US history. The dismantling of the apartheid system of Jim Crow and the push for Civil Rights laws, Voting Rights laws, environmental protection laws, LGBTQ Rights, etc. All of these efforts were made in ways that bound people together in manners that pushed towards an integrated multicultural system that was a successful blend of the best of all cultures.
The dream of multiculturalism goes back further than Alexander's dream. A great Pharaoh of Egypt, a millennium prior, held a dream of multiculturalism that bound some of the early cities and settlements together into the first nations and empires. This Pharaoh was Akhenaten (Amenhotep IV). While this great Pharaoh was successful in numerous areas, successfully establishing integrated administrative systems that could stand the test of time in an era of conflict and scarcity was not one of them unfortunately. The administrative system designed by Alexander in applying the ancient dream of Akhenaton restructured the world in manners still feel today. And could have created a system that revolutionized the world to a higher degree than it already has in our world today, if Alexander had survived to oversee administration of his empire.
We may never know what Greek Hellenism would have evolved into if Alexander had survived; we may never know what Egyptian multiculturalism could have grown into if Akhenaton had been a stronger organizer, or if the Romans had retained their republic instead of converting to an empire. Something we do know, however, is that American cultural heritage with the Greco- Roman history, and by extension Egyptian, Persian, Babylonian, etc heritage/history; has the potential to push forward in actualizing the dreams that were outlined by a great leaders like Alexander and Akhenaton. In which multiculturalism unifies human civilization is a collective that protects the individual and the social culture, bringing out the best of all. Or we risk repeating the same cycle of collapse and regression seen in the past with those that chose empire and domination over fellow humans.