According to the U.S. and World Population clock, the U.S. population reached the 300 million mark at 11:46 G.M.T. (Greenwich Mean Time) on October 17, 2006. The event was met with a mediocre response compared to the federal response to the 200 million mark. When the population reached 200 million in 1967, President Lyndon Johnson held a news conference at the United States Commerce Department, to "hail America’s past and to talk about the challenges ahead". However, Commerce Secretary, Carlos Gutierrez, had this to say, "I would hate to think that we are going to be low key about this...I would hope that we make a big deal about it."

Indeed it is a "big deal," the United States is now the third most populated country in the world, trailing behind India and China, with populations well over 1 billion. In addition, the United States population, when compared to the rest of the world, is steadily increasing by at least 1 percent a year.

However, the United States demographics have shown more specific changes than just an increase in population. 80% of the population now lives in a metropolitan area. Moreover, New Jersey is now the most populated state, with 1,134 people per square mile, as opposed to Alaska, the least populated state, with just 1 person per square mile. In the time span between the 200 million mark and the 300 million mark, the percentage of foreign born citizens has grown from 5% to 12%. Indeed the most drastic change is America's immigrant status; in 1967, the majority of U.S. immigrants were Italian, while in 2006 the majority of immigrants come from Latin America.

Former Atomic Chairman, David E. Lilienthal, once said, "A population of at least 300 million ... I now believe, threaten the very quality of life of individual Americans." Obviously 100 million Americans would beg to differ.