THE first surprise came in June, when the Pew Research Centre reported that Asians were immigrating to the United States in higher numbers than Latinos. The second came after the presidential election, when some exit polls suggested that Asian-Americans were second only to blacks in their proclivity for Barack Obama. (A new report this week estimated that 71% voted for the president, roughly the same as the Latino figure.)

Recent political soundings in racial demography have focused on Latinos. That is no surprise; they are projected to grow from 17% of the population today to nearly one-third by 2060. But the Asian-American story is a fascinating subplot. Since a loosening of immigration laws in 1965, Asians have risen from less than 1% of the population to nearly 6%. They are richer, better-educated and more optimistic than other groups, including whites. And in the past 20 years the share of them voting for Democratic presidential candidates has more than doubled.

But is the term “Asian-American” anything more than a convenient shorthand? The ancestral lands of the people it covers are home to most of the world’s population. Unlike the vast bulk of Latinos, Asian-Americans speak different languages and worship different deities from one another. Almost two-thirds of Latinos are of Mexican ancestry. But the biggest Asian subgroup, Chinese-Americans, make up just 23% of Asian-Americans.

Politically, Asian-Americans range from the strongly Democratic (Indians) to the evenly split (Filipinos). Economically, all big Asian groupings do better than the average American. But the income of the median Indian household is 175% that of the median Korean. “The generic ‘Asian-American’ category disguises what is going on more so than other segments,” says Mark DiCamillo, a San Francisco-based pollster. Just 19% of Asian-Americans use the term to describe themselves.

Tri Ta is not one of them. On December 12th Mr Ta was inaugurated as America’s first Vietnamese-American mayor in the small Californian city of Westminster. Interviewed in his office, beneath pictures of his guiding lights (Plato, Sun Tzu, the Buddha), Mr Ta says that there are “commonalities” among Asian-Americans but that the term does not mean much to him.

Westminster, part of a stretch of Orange County known as “Little Saigon” since the arrival of thousands of war refugees in the mid-1970s, is 40% Vietnamese. Its streets teem with coffee shops and pho noodle joints. But the Pew report notes that just 11% of Asian-Americans live in Asian-majority districts. Chinatowns may be fun for tourists but Chinese-Americans are more likely to be found in the suburbs, and elected Chinese-American officials to be serving Chinese-minority constituencies.

As an immigrant to America (he arrived in 1992), it is perhaps unsurprising that Mr Ta would describe himself more readily as Vietnamese- than Asian-American. But, says Karthick Ramakrishnan at the University of California, Riverside, many second-generation Asian-Americans are happier with the generic term and less concerned with national ancestry than their immigrant parents. Moreover, in surveys Mr Ramakrishnan has found evidence that Asian-Americans of all stripes believe that they share a common culture.

Perhaps the best way to understand the term Asian-American, says Eric Liu, a Chinese-American author and former adviser to Bill Clinton, is as a “classically American invention”: a manufactured identity that grants those it happens to include a level of political and cultural power they would not otherwise enjoy. Mr Liu says the various Asian subgroups in Seattle, his home town, are too small for any one to wield real power. But united as “Asian-Americans”, they are a force in civic life.

Twelve Asian-Americans will sit in the next Congress, the most ever. But the true impact of Asian-Americans on public life has probably yet to be felt: the median age of the second generation is only 17. Mr Liu says students he knows have a far more fluid sense of collective self than their elders. The only identity adequate to contain their diversity, he adds, is “American”.