In fact, this perception began departing from reality some 50 years ago in most of the region, and today it is true for only a few nations: Haiti, Honduras, Bolivia and maybe Nicaragua. By 1970, the larger nations like Brazil, Mexico, Colombia, Venezuela, Chile and Peru had all witnessed the emergence of sizable middle classes. Others, like Argentina and Uruguay, had been, for all practical purposes, middle-class societies since at least midcentury (although the Argentines in later decades worked hard at regressing.)

But there was always a gulf between those societies and the United States. Until quite recently, the Latin middle classes made up barely one-third of the population, and some of their most prominent members — Che Guevara in Argentina, Fidel Castro in Cuba, Salvador Allende in Chile — made political careers out of the cause of eradicating inequality. That cause was shared by thousands of students, union leaders, academics and middle-of-the-road politicians, who found their own way of life morally intolerable and politically untenable.

After years of frustration and failure, at the end of the 20th century something began to change. And over the last 15 years the trend has become unmistakable. According to one definition of the middle class used in recent research by the Organization for Economic Cooperation and Development, the middle class is in the majority in Chile, Brazil, Mexico, Uruguay, Costa Rica and to a lesser extent Colombia. In the 1960s and ’70s, even after decades of robust growth, those middle classes were barely at 30 percent; today in Mexico, Brazil and Chile the figures range from 55 to 60 percent.

Yes, it is still a slim and precarious majority, and it is not your mother’s middle class — as secure and well-off as in Europe, North America, Japan or South Korea. The Latin middle class still struggles, with living standards far behind those of the local affluent. But a middle class it is nonetheless: with cellphones and used cars; with tiny but well-built homes with every appliance; and with modest but deeply enjoyable holidays at the beach.

Consumer markets have expanded. The World Bank and the O.E.C.D., writers like this one and universities like the Getulio Vargas Foundation in Rio de Janeiro have produced reams of data and analysis about the size, depth and lasting power of this middle class. Politicians know they can be elected only if they connect with that class and are doomed when they appeal exclusively to the poor, who, though now a minority, are still too large a share of the population.

So it can be said that much of Latin America has arrived: it is democratic, with a slight but growing majority of its people prosperous, competitive and possessing international ambitions (real, though not always realistic).

But reducing poverty and building broad middle classes do not automatically reduce inequality. The statistical measures of inequality known as Gini coefficients have begun to fall slightly in Latin America, but remain the highest in the world, with the wealthiest 1 percent, 5 percent or 10 percent of the population controlling incredibly high shares of total wealth or income. In Brazil, Chile and Mexico, which together account for nearly 70 percent of the region’s G.D.P. and population, the wealthiest 10 percent held an average of 42 percent of national income in 2008-9; the equivalent figure for the United States was 29 percent.