When the symbolic 200 millionth baby was born in Atlanta, Georgia, in 1967, a cadre of photographers met President Lyndon Johnson to mark the occasion and focus on what was needed to sustain the country at 300 million. At 300 million the mood was much more subdued, but there was no denying the U.S. was still growing: unlike Europe, where birth and death rates more or less evened out, the U.S. population was growing by 1.8 million a year at the time, and attracting close to another million new residents — a 2.6% increase each year.

On this day, October 17, in 2006, the United States Census Bureau estimates the population of the United States reached 300 million.

In between the last 100 million, several demographic shifts had taken place in the U.S. A lot of the new population settled in the Southwest. Arizona, for instance, gained a million new residents between the two dates. Retiring Baby Boomers filled up Florida, tripling its population, and city suburbs overtook city centers in total residents. That last trend appears to be reversing, but all have acknowledged that the next 100 million, scheduled to come around 2043, will be harder to support than the past ones.