The concept of ‘nationality’ is myth institutionalized. Culture-plus.
Culture is a myth existing in the subtleties of our everyday lives. Known by everyone, taught by everyone; and, yet it remains a bit invisible to those very ones who know and teach it. Nationality is is an institutionalized mythological narrative taught publicly, in a systematic fashion. Simple things like reciting a pledge of allegiance at the start of every school day.
Three types of nations may be distinguished. Old, natural nations like Britain, France, Spain, etc. New nations that emulated the nationalistic practices of others; and, the third kind are forced into nationhood by virtue of being ex-colonial states granted independence. Forced nations are those nations founded on the assumption that immemorial antiquity can be constructed, taught, and ultimately naturalized into a population.
America is a unique case.

“The soil of America absolutely rejected a territorial aristocracy.” The inhabitants “hardly know one another, and each man is ignorant of his nearest neighbor’s history…Wealth circulates with incredible rapidity, and experience shows that two successive generations seldom enjoy its favors.”
Alexis de Tocqueville (French diplomat; b. 1805 – 1859)
The circulation of wealth is not a condition common to forced nations. Americans enjoyed a bourgeois liberty, “not the aristocratic freedom of their motherland, but a middle-class and democratic freedom.”
They had learned to combine democracy and liberty as the French had not. The French had to suffer a democratic revolution. Americans did not and thus “were born equal instead of becoming so.” This ignores the slave-holding practices of America at that time, but the idea is that your bloodline does not determine your life. There was no landed gentry or fiefdoms in America.
There is an absence of an American socialist or militant-working class tradition. The white immigrants could pursue their middle-class goals freely, unencumbered by a feudal tradition. Social homogeneity kept most Americans from systematically thinking about class differences. The American political culture lacked the European social categories which may be necessary to allow for the expression of such antagonism.
Hartz even argues that the failure of the bourgeois to develop class consciousness left American workers ideologically crippled. Because, there were no feudal institutions to attack, U.S. liberals, unlike European liberals, could entirely reject the idea of powerful government. America did not have it as a weapon because they never had to use against an older order.
*The Liberal Tradition in America: An Interpretation of American Political Thought since the Revolution; Louis Hartz, 1955.
Widespread economic wealth had a major role in sustaining the liberal character of U.S. political thought. Social pluralism and separation of residence from workplace can be attributed, at least in part, to the openness and fluidity of a liberal society.
The American liberal tradition has been very effective in limiting U.S. political development because ideas and behaviors, words and deeds, have mutually constrained one another.

The New England Calvinist Jeremiad made a contribution to the dominance of a liberal consensus. It pointed out New England’s and, later, America’s failings: the sins of the people. The more often the preachers named the nation’s sins and punishment, the more strongly they asserted that the nation’s special mission as “god’s chosen instruments.” This mission was essentially individualist and capitalistic.
“New England evolved into a middle-class culture…a commercially-oriented economy…sustained by the prospect of personal advancement.”
The American Jeremiad; Sacvan Bercovitch, 1978.
Here is a cultural foundation for the American social order (the ‘spiritual cohesion’ that comes only from a ‘social ideal’) which such a purely secular concern with ‘personal aggrandizement’ could not provide.
Through the Jeremiad, Americans came to see a special place for their country in the world, as well as envision it having a sacred history. As a result, the Puritan rhetoric of social criticism re-affirmed a belief in the legitimacy of the American regime by promising to purge it of its defects.
Gellner’s discussion of nationalism revolves around the transition from Agrarian to Industrial. Industrial civilization is based on the explosion of economic/scientific growth rather than stable technology. Population growth in the industrialized world is no longer Malthusian.
The two principles of political legitimacy in industrialized societies are 1) economic growth and 2) nationalism. Regimes are acceptable if they can, over a period, engender growth, if not they lost authority.
We are egalitarian because we are mobile (as a society); we are not mobile because we are egalitarian. Mobility is imposed on us by social circumstance. Growth entails innovations and new technologies, creating and relinquishing jobs. Growth societies cannot have a stable occupational structure. These societies acquiesce members by giving confident, justified expectations of moral improvements as opposed to inciting terror or superstition. Everyone climbs the ladder, gets a promotion.
The modern occupational structure professes to be egalitarian, within a upwardly mobile professional sphere. Within that sphere, however, we are to be anonymous, per se. Leave your personal problems at home, right?

The person you are at work must censor and behave differently than the person you are at home. Well, at least for many of this surely remains true. Remove a subsistence economy and you stop people from procuring their own foods and goods. Replace that economy with a cash economy and now people hold jobs to be paid a wage that they may use to purchase the things they need. This is the counter-intuitive, semantic nature of work in industrial societies.
All this reduces to the capacity to articulate and/or comprehend context-free messages. This is the metaphorical antithesis of what are brain does, particularly when interpreting meaning from words. Context provides meaning. Personal context can become a moot point in modern, professional environments as the implication is that professionalism is not the same as authenticity. Professionalism involves carrying oneself in a posture: posturing. Authenticity is the posture you take when no one is looking. Crossing your legs at work versus going spread-eagle on the couch to get comfy.
One is a panto and one is what it is.
Nations and Nationalism; Ernest Gellner, 1983