Is this a thing? Or do people just role their eyes? It seems to be a thing, worth considering, but possibly taking a skeptical look. The American Revolution made us different, a revolt creating a social contract based on an idealistic ideology summed up as exceptional. Alexis de Tocqueville called up exceptional, apparently with a straight face, including our Puritanical origins and commercial habits--including our lust for money. Lincoln's Gettysburg Address made us proud, and suggested a national purpose based on Founding documents of equality and freedom. Dick Cheney called us exceptional; what could possibly be wrong with that?
We're coming on the 400th anniversary of the creation of the House of Burgesses for the Jamestown Colony (1619), one definition of electoral democracy. It will also be the 400th anniversary of slavery in America, also at Jamestown Manifest destiny was the concept of expanding across the entire continent, the term coined by John O'Sullivan just before the Mexican-American War. This sounds much better than attacking Canada, Mexico and native Americans. Woodrow Wilson called for "making the world save for democracy," before a declaration of war in 1917; this was followed by FDR's "arsenal of democracy" before World War II (when the Soviet Union was on our side). American values have been part of foreign policy for a couple of centuries. Big events happened: the Bill of Rights, Lewis and Clark, Erie Canal, transcontinental railroad, Marshall Plan, walking on the moon. Famous painting reinforced the concept, such as John Trumbull's Declaration of Independence and Emmanuel Leutze's Washington Crossing the Delaware (neither historically accurate but creating American mythology).
The concept is reasonable as long as the dark side is considered, including not only the history, but the institutions, culture, and psychology. The transcontinental railroad, for example, included the biggest scandal of the 19th century, Credit Mobilier.