What is American exceptionalism?

In its classic forms, American exceptionalism refers to the special character of the United States as a uniquely free nation based on democratic ideals and personal liberty. Sometimes this special character is inferred from the nature of American political institutions founded in the 1776-89 period–the declaration of independence (1776), revolution (1776-83), constitution (1787) etc. Thus the “revolution” and its aftermath freeing the US from British control are important in ideas of American exceptionalism. But often the political differences are said to be underpinned by material differences brought about by the wealth/resources of the United States, sometimes seen as a direct product of the freedom of the American people, but by others as the product of the inheritance of the North American continent’s abundant resources. This is the frontier version of the theory, and this and the ideas of social mobility and immigrant assimilation  are closely tied to this set of ideas of American material prosperity. Many aspects of American history may be left out or distorted in the traditional narratives–particularly the histories of Amerindian peoples and the contribution of other ethnic groups that preceded the Anglo-Americans, e.g. Hispanics. Race and slavery are seen as tragic exceptions, and the abolition of the latter was viewed as a partial resolution, encompassed in Lincoln’s idea of a “new birth of freedom” in the Gettysburg Address.