President George W. Bush welcomed the expanding US population yesterday, which hit the 300 million mark on Tuesday, as fresh evidence the "American Dream" remains a beacon of hope.
"Our continued growth is a testament to our country's dynamism and a reminder that America's greatest asset is our people," Bush said in a statement.
The population landmark caps four decades of growth fueled mainly by Hispanics and other immigrants, the Census Bureau said.
The 300 millionth American clocked in at 7:45am on Tuesday, the bureau said, and could have been a newborn, an immigrant coming across the border or someone flying into the US.
When the official population clock hit the big figure, bureau employees cheered, clapped and joked about whether the actual resident was male or female.
"It was a historic occasion. I had to be there," said Anthony Petty, a bureau staffer.
"It's like a birthday. You stop to think, to remember and to look forward," said Howard Hogan, of the bureau's demographic program.
The bureau calculated the exact time of arrival of the 300 millionth US resident based on prevailing birth rates, death rates and rates of international migration.
"There is no way of knowing what particular person it is. This is an estimate. It can be a person just born or entering the country," stressed Preston Jay Waite, the bureau's associate director for the decennial census.
Unlike the pomp and circumstance that greeted the 200-million mark in 1967, federal officials did not organize any major celebrations for Tuesday's landmark, which comes amid a raging debate on immigration and concerns over the potential environmental impact of a larger US population.
Experts say that one reason the population has grown so fast in the past 39 years, as reproduction rates have slowed, is the influx of immigrants, many of them illegal, coming into the country especially in the past 15 years.
The bureau estimate includes all who reside in the US -- including US citizens and residents, legal and illegal.
"About half of the growth in the US population is due to Hispanics, and well over half the growth is due to immigrants and their children," said William Frey, a demographer at the Brookings Institution in Washington.
He said the growth represents a return to the US' immigrant past and a return of its image as a "melting pot."
"This is important because it's a symbol of where America is going in the new century," he said.
Global Insight chief economist Nariman Behravesh said the fact that the US population is growing faster than that of other developed countries is very good news.
"It will allow us to better deal with the budgetary pressures [Social Security, Medicare] related to our aging population," he said. "Given our large land mass, we have had no problem absorbing all these new people. In fact, our population could double and we would still have a lower population density than Japan and most European countries."
Some, however, are expressing concern about the environmental impact of the growing US population, which is expected to reach 400 million by mid-century and 600 million by the end of the 21st century.
"In some ways, you have to appreciate the kind of growth and prosperity in your country, but on the other hand, I see what kind of implications this has for the natural environment," said Vicky Markham, director of the Center for Environment and Population, based in Connecticut.