Here is a recent posting from the U.S. Census Bureau! Enjoy.
United States Population Reaches Milestone — Shortly after 2:29 p.m. EDT today, the U.S. population clock will reach a milestone that is very meaningful to mathematical statisticians: it will show there are 314,159,265 residents, or pi (3.14159265) times 100 million. Pi is a mathematical constant that is the ratio of a circle’s circumference to its diameter. “This is a once in many generations event…so go out and celebrate this American pi,” said Census Bureau Chief Demographer Howard Hogan. Internet address: <http://www.census.gov/main/www/popclock.html>.