An anonymous reader writes "The number of Americans will surpass 300 million this month, a milestone that raises environmental impact questions for the only major industrial nation whose population is increasing substantially. The US census bureau says the 300 million mark will be reached 39 years after US population topped 200 million and 91 years after it exceeded 100 million. That makes US the third most populous country behind china and india. It is noteworthy that sheer number of human beings do not necessarily have the heaviest impact on the environment. Instead environmental impact is a calculation that involves population, affluence and technology. The US consumes nearly 25% of the world's energy though it has only 5% of the world's population and has the highest per capita oil consumption worldwide. Each American produces about 2.3 kg of trash a day, a rate about 5 times that in developing countries."