AMONG America's three-year-olds, a revolution is afoot. Children of that age are turning the country's demographics on its head. According to a recent study from the Census Bureau, the majority of them are now from groups normally considered minorities, chiefly Hispanics and blacks. The latest release of data from last year's decennial census confirms that whites still constitute a slender majority, 54%, of those under 18, and a larger one, 64%, of the population as a whole. But America's transformation into a much browner, more suburban, more southern and western place is rapid and relentless.

Over the past decade America's population has grown by 9.7%, to 309m. Minorities accounted for 92% of that growth. The ranks of Hispanics swelled by 43%, to 51m. The Asian population grew at the same rate, to 15m. Blacks increased in number by 11%, to 38m. All minority groups put together jumped by 29%, to 112m. Minorities now form the majority in America's two most-populous states, California and Texas, as well as in Hawaii, New Mexico and Washington, DC. They account for the majority of children in six more: Arizona, Florida, Georgia, Maryland, Mississippi and Nevada. And their numbers are growing particularly fast in previously lily-white places such as Iowa and New Hampshire.

Meanwhile America's white, non-Hispanic population grew by only 1.2% from 2000 to 2010. In 15 of the 50 states, it shrank. California lost 5% of its whites; New Jersey and Rhode Island both shed 6%. The number of white children fell in 46 states, for an overall decrease of 10%. Whites, explains Bill Frey of the Brookings Institution, a think-tank, are older, have fewer children anyway and make up a relatively small proportion of immigrants, so their share of the population is destined to go on falling.

The giant sucking sound emanating from the South and West, another leitmotif of American demographics, continues unmuffled. Both regions grew by 14%, while the north-east and the Midwest managed just 3% and 4% growth respectively. People are fleeing the cold: there is a strong correlation between the average temperature in January and population growth, notes Edward Glaeser, a professor of economics at Harvard University. He also attributes the rapid expansion of cities like Atlanta, Dallas, and Houston to their cheap, abundant housing.

Even in the sunbelt, however, many rural areas are losing population. The trend is particularly acute in the plains states, but also pertains in much of the Midwest and the South. The proportion of Americans living in urban areas rose from 93.2% in 2000 to 93.7% last year, with big cities growing faster than small ones. Most of this growth occurred in the suburbs rather than the inner cities, Mr Glaeser adds, with the more prosperous metropolitan areas and those with better educated residents growing especially fast. Areas with lots of manufacturing grew more slowly.

Michigan, with its long-suffering car industry, was the only state to see its population shrink over the decade, albeit by less than 1%. (Puerto Rico, an American territory with economic troubles of its own, lost 2% of its inhabitants.)

What all this means for politics is the subject of some dispute. Right-wing analysts herald the ballooning population of the Republican-leaning states in the South and West and the relative stagnation of the Democratic bastions in the Midwest and north-east as proof of the superiority of Republican policies. What is more, they crow, faster growth is bringing more seats in the House of Representatives to Republican states, which could help to cement their current majority. Conservative Texas, for example, is gaining four seats in the reapportionment set in train by last year's census; liberal New York is losing two.

But Democrats counter that the growth the Republicans are celebrating comes from natural Democratic constituencies. Minorities, they point out, tend to vote Democratic, whereas the dwindling white, rural population is largely Republican. By this logic, Democratic infiltrators are gradually undermining Republicans' control over their territory from within. Barack Obama, after all, carried previously Republican-leaning western and southern states such as Colorado, Nevada, North Carolina and Virginia on his way to the White House in 2008. If he can maintain his share of the vote among blacks and Latinos, he will be hard to beat in 2012.