From 1900 to 2000, the U.S. population quadrupled while the economy expanded 26-fold. As a result, U.S. per capita consumption of materials rose from 1.9 tons in 1900 to 5.6 tons in 1950 to 12 tons in 2000. In Making the Modern World, the University of Manitoba natural scientist Vaclav Smil cites data suggesting that global annual output now comprises about 10 billion different products. Nevertheless, the majority of people on the planet have not yet achieved the material abundance enjoyed by Americans, Europeans, and the Japanese. Can humanity find, transform, and deploy enough resources to lift those people into affluence? Reason Science Correspondent Ronald Bailey delves into Smil's primer on modern material flows seeking the answer.