While prediction is obviously an inexact science, most demographers predict that world population will peak at 9-9.5 billion around 2050, and then possibly even start declining. Most of the growth will be in Africa and Asia. As Stephen mentioned, most of Europe is either declining in population or soon will be. Russia's population is in free fall. They have 143 million now, but are predicted to have only 110 million in 2050. The U.S., while growing, will remain relatively empty for many decades at a minimum. If I remember the math correctly, we could move everybody in the world to the U.S., and still have a lower population density than that of Bangladesh.