U.S. Population Passes 300-Million Milestone

[Bob in a quantum-state-of-faith]

http://www.voanews.com/english/AmericanLife/2006-10-18-voa43.cfm

The population of the United States officially passed the 300 million mark on Tuesday (October 17). While it took almost two centuries for the U.S. population to reach 200 million, it took just 40 years to add the last 100 million.

[Sibling Lambicus the Toluous]

While it took almost two centuries for the U.S. population to reach 200 million, it took just 40 years to add the last 100 million.

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Why would one expect any different?

If the birthrate per 1000 population per year and morbidity are generally constant, then the total population would behave like a compound interest exercise... increasing quicker (in terms of net additional people per year) as time goes on, but at a fixed growth rate (in terms of percentage increase per year).

However, infant mortality has improved over the past 100 years or so, and average lifespans have increased; both of these would increase the growth rate.

Actually, I'm surprised that the US isn't at 400,000,000 by now.

[Kiyoodle the Gambrinous]

I think the biggest reason behind this number is the immigration increase in the past few decades...

(although the birth/death rates are important as well)

[Aggie]

Heh, is there a calculation by human biomass anywhere?  THAT'D look interesting, considering obesity rates have also gone up in the last few decades...