In 1909 Herbert Croly, the founding editor of The New Republic and one of the patron saints of the twentieth-century progressive-liberal tradition, published his manifesto, The Promise of American Life. "The Promise of America," he wrote, "has consisted largely in the opportunity which it offered of economic independence and prosperity." According to Croly,
The native American, like the alien immigrant, conceives the better future which awaits himself and other men in America as fundamentally a future in which economic prosperity will be still more abundant and still more accessible than it has yet been either here or abroad ... With all their professions of Christianity their national idea remains thoroughly worldly ... The Promise, which bulks so large in their patriotic outlook, is a promise of comfort and prosperity for an ever increasing majority of good Americans.
The idea that the promise of American life lay in widespread material prosperity as much as in civil liberties or political democracy is an old one. As Croly pointed out, in 1782 Hector St. John de Crèvecoeur wrote in his Letters From an American Farmer,
What, then is the American, this new man? ... Wives and children, who before in vain demanded of him a morsel of bread, now, fat and frolicsome, gladly help their father to clear those fields, whence exuberant crops are to arise to feed and to clothe them all; without any part being claimed, either by a despotic prince, a rich abbot, or a mighty lord ... From involuntary idleness, servile dependence, penury, and useless labor, he has passed to toils of a very different nature, rewarded by ample subsistence. This is an American.
The equation of America with widespread middle-class prosperity persists today. Of the millions of people who came to the United States following the resumption of large-scale immigration in the last third of the twentieth century, a few were refugees from political or religious persecution. Most, however, wanted what previous generations of European immigrants had sought: "America has been peopled by Europeans primarily because they expected in that country to make more money more easily," Herbert Croly wrote.
America, then, is not simply the land of political liberty. It has always also been an economic paradise for the middle class—at least until now.
What exactly does it mean to say that the United States is a middle-class society?
In the pre-modern societies of Europe the terms "burgher" (German) and "bourgeoisie" (French) referred to the minority of largely urban merchants and professionals who were above the peasant majority and below the minority of landholding aristocrats. But when Americans talk about the middle class, they are not talking about burghers or the bourgeoisie. What makes the United States and similar societies middle-class is the economic predominance of the middling sort, no matter what their major source of employment happens to be.