Geography and climate. The western US is very mountainous with lots of desert areas.[0] The east, in comparison, is very flat with plenty of water and climates

Geography and climate. The western US is very mountainous with lots of desert areas.[0] The east, in comparison, is very flat with plenty of water and climates more suitable for farming.[1] Population in the west is therefore more clustered around the few areas suitable for human settlement. If you're talking about the racial population patterns, that's a product of history and geography (again). European settlement of the US started in the north-east, African slaves were brought mainly to the south-east and Hispanic migrants come largely from the south, across the border with Mexico. [0] http://upload.wikimedia.org/wikipedia/commons/2/2d/USA_topo_en.jpg http://upload.wikimedia.org/wikipedia/commons/2/2d/USA_topo_... [1] http://www.okatlas.org/okatlas/weather/climate/usa/climate.gif http://www.okatlas.org/okatlas/weather/climate/usa/climate.g...