Dan Rather

Emanuel Plata, born last week in New York City, may or may not have actually been the 300 millionth American, as celebrated in bold letters on the blanket that covered his tiny form. There were, after all, plenty of babies born around the time when the U.S. Census Bureau's population clock flipped to that big, round number - including, in true Big Apple fashion, another New York baby laying claim to the title.

In symbolic terms, though, little Emanuel represents a perfect choice. He came into this country, as so many do, by way of the most diverse borough - Queens - of our most diverse city. And he was, as some had predicted the baby 300 million would be, the child of Mexican immigrants.

When the 100 millionth American was born some time in 1915, Woodrow Wilson was president and this was still a largely white, European nation, demographically and culturally. When the 200 millionth American arrived in 1967, Lyndon Johnson was in the White House and various ethnic groups - including the African-Americans who had been here virtually from the start and the Native Americans who were here before any of us - had begun to find their voice in the larger culture.

Majority

Now America faces a future where the European descendants who founded this nation and who have for so long dominated its culture and demography may no longer constitute the overwhelming majority of the population. As we have seen in recent years, and this year especially, there will be a period of adjustment along the way to the destiny prescribed by these demographics.

As we debate what the future should and will look like, we will need to be careful to distinguish legal immigration from the illegal variety. And it seems clear that we will also need to develop a coherent and fair immigration policy - such has been an ongoing challenge for this republic - that both clarifies and reflects this understanding.

An honest reckoning with economics is a necessary part of this debate, too. A lot of the people now coming into the U.S. are poor. And their labour is vital to whole industries. Are they benefiting disproportion-ately from the social safety net - or helping to prop up the entitlement programmes of a nation that otherwise is ageing rapidly?

Here at 300 million, culture and demographics are not the only hurdles in our quest for a more perfect union. There is also the issue of sheer mass - of population taken alone, and what these numbers mean.

Third largest nation

America is the most prosperous nation the world has ever known, and the third-largest nation on Earth in terms of landmass. It will be some time before this country comes up hard against the limits of its growth. But as we look at the larger picture, we might also ask ourselves if the world can continue to sustain a nation that consumes, per capita, by far the largest share of Earth's resources. As other large nations, such as India and China, grow in population and economy, this question is bound to become more pressing.

The answers to all these questions might hinge on the answer to a larger and more subtle question: As America grows and diversifies, will we keep communicating with one another? Will we find shared forums to talk and hash things out, or will we retreat into niche interests and separate communities? In short, will we continue the democratic tradition of seeking and forging consensus on the most important issues facing us, or will we allow ourselves to become ever more divided - balkanised culturally, demographically and politically?

There are a lot of questions facing America, but luckily there are 300 million answers. Welcome, Emanuel Plata, to the greatest experiment in history.

Dan Rather is an American television broadcaster.