here are many theories surrounding the origin of American exceptionalism. The most popular in US folklore, being that it describes America’s unique character as a “free” nation founded on democratic ideals and civil liberties. The Declaration of Independence from British colonial rule is the foundation of this theory and has persevered throughout the often violent history of the US since its birth as a free nation.
Over time, exceptionalism has come to represent superiority in the minds and hearts of Americans. Belief in their economic, military and ideological supremacy is what has motivated successive US governments to invest in shaping the world in their superior image with little or no regard for the destruction left in the wake of their exceptional hegemony.