World of 7 Billion (Human Population Dynamics

The map shows scribbles of different colors representing population density of the world. It also shows pictures of some of the most populous cities in the world. Each country is colored according to its average annual gross national income per capita, using categories established by the World Bank (see National Geographic.com -Interactive map). Some nations— like economic powerhouses China and India—have an especially wide range of incomes. But as the two most populous countries, both are lower middle class when income is averaged per capita.