Your average American generally and your average flag-waving, parade-attending American specifically, is likely to be unaware of two facts.

First, when Republicans and Democrats, "liberals" and "conservatives," in government and Big Media reference America, they have something very different in mind than that entertained by everyday Americans when the latter refer to their country.

Secondly, Republicans and Democrats, "liberals" and "conservatives," in government and Big Media, despite the appearance of consistent disagreement, actually endorse one and the same conception of America.  It is the conception of America that, for reasons that will later be disclosed, is championed by the Mono-Party, the Regime, or, as I call it, the Big GAME (Government-Academic-Media-Entertainment complex).

From this stance, America is an Idea.

America is depicted as the first and only nation in all of human history to have been "founded" upon a "principle" or "proposition."

Thus, like any other idea, like any other mental phenomenon, it is fundamentally immaterial.  What this in turn means is that while America is typically identified with certain particulars like a landmass, a government, a legal order, etc., ultimately it is a trans-historical, trans-cultural Idea that just happens to be instantiated—imperfectly instantiated—in such contingent, material forms.

In the last analysis, then, America is an Idea that, as such, is borderless.

As to the exact character of this Idea, proponents differ amongst themselves. Usually, however, America is conceived as a creed affirming "human rights," "Democracy," ideals of Freedom and Equality, or something along the lines of these abstractions.  But however its proponents decide to construe the Idea, they agree that America's identity is anchored in this timeless, immutable Essence.

This Idea or Essence is also normative.  It is ethical: The Idea is something to which all human beings the planet over should aspire.

In this vision of America-as-Idea, we see ontology and ethics converge seamlessly: America, ultimately, is a moral reality.

America-as-Idea also implicates its own peculiar epistemology.  Because the Idea purports to be a timeless object of discovery, it is said, as Jefferson says of our "unalienable rights," that it is "self-evident."

That is, the epistemology is unmistakably and inevitably rationalist.  Knowledge of the Idea is a priori, independent of experience. Hence, in theory, it is accessible to all rational creatures in all places and at all times.

This conception of America is the official, contemporary understanding promoted by The Big GAME, the Regime.  It is the vision of leftist ideologues and the Deputized Right, of "progressivism" and Big Conservatism (the Big Con) alike.

The question as to why or how it is that partisans of seemingly different stripes have managed to coalesce around the same conception of America can be answered easily enough even on the dubious assumption that such partisans really are of different stripes:

From the vantage of America-as-Idea, America is an ideological or creedal nation.

In other words, America so conceived is an ideology.