The 300 millionth American? Later this year, the U.S. population will reach a milestone. A look at how the nation has changed since we hit 200 million in 1967.

Sometime in October, if the experts are right, the 300-millionth American will be born. How can experts make such a prediction? Well, as of mid-January, the population of the United States was almost 297,900,000, according to the Census Bureau.

With a baby being born every 8 seconds, someone dying every 12 seconds, and the nation gaining an immigrant every 31 seconds on average, the population is estimated to be growing by one person every 14 seconds. At that rate, the total is expected to top 300 million about eight months from now.

"You end up with a number in October," says Katrina Wengert, a demographer and a keeper of the Census Bureau's official Population Clock. The clock is actually a contrivance, based on statistical calculations, since the Census Bureau doesn't actually send a representative to all the nation's hospitals to count people as they're born, or to the borders or airports to count each new immigrant.

But rest assured that hospital publicists, baby-food manufacturers, public officials, and countless others are already guesstimating the growth rate to anoint any number of unsuspecting newborns--11,000 are born every day--as the mythical American who pushed the nation's population to 300 million. (Of course, the 300-millionth could be an adult immigrant, even one who crossed the border illegally, but statistics favor a native-born baby.)

CELEBRATING 200 MILLION

In 1967, when the population reached 200 million, Life magazine sent 23 photographers to locate the baby and devoted a five-page article to its search. Instead of deciding on a statistically valid symbol of the average American newborn, the magazine chose to find a baby born at precisely the appointed time, according to the Population Clock.

Life ended up immortalizing Robert Ken Woo Jr. of Atlanta, whose parents, a computer programmer and a chemical engineer, had emigrated seven years earlier from China.

Woo turned out to be a good representative of the American Dream: He graduated magna cum laude from Harvard University and is a lawyer. Now 38, he still lives in Atlanta with his wife, Angie, also a lawyer, and their three daughters. "He did feel an obligation to do well," Angie Woo says. "But I think he would have done well, regardless."

Given the demographic changes recorded in the 20th century, the 300-millionth American will likely be a very different person from the prototypical 200-millionth American in 1967, or in 1915, when the nation's population passed 100 million.

Some demographers, taking into account current statistics, have already come up with a description of the symbolic 300 millionth: Since California is the state producing the most newborns, they say the baby will be a Californian; since more than 50 percent of the newborns in California are male, the 300 millionth will be a boy; and with Hispanics having the highest birthrates in California, he will be Hispanic.

"The 300 millionth will be a Mexican Latino in Los Angeles County, with parents who speak Spanish at home and with siblings who are bilingual," says William Frey, a demographer at the University of Michigan.

"This is a far cry from the 200-millionth person who was born in the late '60s--probably a white son to middle-class suburbanites in Los Angeles or New York City," says Frey, rejecting Life magazine's determination, "and different from the 100-millionth person born in the late 1910s, perhaps to a white ethnic city family in New York City or rural family in upstate New York or Pennsylvania."

"The new baby," Frey adds, "is symbolic of America's new multiethnic demography of the 21st century."

Whatever he or she actually looks like, the 300-millionth American will live longer--to 85 or 90 on average, compared with an average life expectancy of 77 today--and in a nation that will be more crowded.

IMMIGRATION'S IMPACT

Today, there are still plenty of wide-open spaces, with about 80 people per square mile in the nation. But density varies widely: Some Texas counties are home to fewer than one person per square mile; Manhattan houses 67,000 people per square mile. "By the time the 300-millionth individual gets to adulthood, many of the cities today we consider small and nice to live in won't be so nice," says Carl Haub, a senior demographer for the Population Reference Bureau.

The U.S., which ranks third in population behind China and India, is still gaining people, while many other industrialized nations are not. (Japan has begun shrinking, officials there announced in December.) Driven by immigration and higher fertility rates, particularly among recent immigrants, the U.S. population is growing by just under 1 percent annually, the equivalent of the entire population of Chicago (2.8 million people).

The Census Bureau projects that even with the nation growing more slowly than ever beginning in 2030, the population will top 400 million less than 40 years from now. And around that time, no doubt the search for a new symbolic American will begin.

HOW WE'RE DIFFERENT "

The U.S. population will hit 300 million this fall, according to the Census Bureau. The graphs at right and below show how the country's population has changed over time.

... And the Mix Is Changing

1920

13.2%

% FOREIGN BORN

Black          9.9%
White         89.7%
Asian          0.2%

RACE/ETHNICITY *

1970

4.7%

% FOREIGN BORN

Hispanic       4.5%
Black         11.1%
Asian          0.8%
White         83.5%

RACE/ETHNICITY *

2004

12.0%

Hispanic      14.1%
Black         12.2%
White         67.4%
Asian          4.1%

RACE/ETHNICITY *

SOURCE: CENSUS BUREAU: WILLIAM H. FREY, UNIVERSITY OF MICHIGAN

Note: Table made from pie chart.