The cold air from the Arctic Ocean to the south and the warm air from the Gulf of Mexico to the north are unimpeded in the middle of the North American continent. What is the main reason?

The Rocky Mountains are in the west of North America, the Appalachian Mountains are in the east, and the Great Plains, the Great Lakes and the coastal plains are in the middle. The terrain is high on both sides and low in the middle, and the air can penetrate the North American continent.

If the Cordillera Mountains are located on the east coast of North America, the natural environment should change greatly, and the central and western regions should be relatively dry, similar to the natural conditions in the western part of the Australian mainland.

The capitals of many countries in South America are built on high mountains and plateaus, because of high terrain, good natural environment and high air quality (such as Mexico City and Brasilia). Now that the economy is developed and the transportation is convenient, they are fully capable of building a new city as the capital. As for being built in the desert, they actually don't want to. The weather conditions are too bad, such as Peru and Ecuador. These countries are small and narrow, and most of them are in the desert. Where else can he build his capital?

Generally speaking, people live by the river, and agriculture, transportation and water sources are very convenient.