The map above projects western and central Europe on top of a map of the United States. The European Union has 510 million people people living within a territory of 4,324,782 square km. Compare that to the Unites States with a population of 324 million people living within 9,883,517 square km of territory – the US is more than twice as big as the EU in area with only 2/3 its population.
What can be inferred from the numbers above is the population density between two areas. The EU has a population density of 304 people per square mile (almost as much as China at 370). Compare that the US with a population density of only 85 people per square mile! The world average population density is 140 people per square mile – if the US increases in population enough meet the world average, it’s population would increase to 530 million people. If the US ever become as densely populated as Europe, its population will swell to over 1.1 billion people – almost as much as present day China!