How can the United States have such a large population of 300 million?

First of all, America is a new continent with a relatively small number of aborigines. During the 400-500 years after Columbus discovered America, new immigrants constituted the main body of the American continent, but the number was still limited. On the other hand, as a population gathering area with a long history, the population of Eurasia has definitely increased. In addition, many environments in the United States are not suitable for human survival, such as the Rocky Mountains, so the population is mainly concentrated in the narrow strips of the east, south and west coasts, while the vast central part is sparsely populated. Secondly, due to cultural and political differences, many Asian cultures encourage family prosperity, while white Americans, mainly European immigrants, do not have this idea. In addition, the strategy of having more children in China put forward by Chairman Mao at the beginning of the founding of the People's Republic of China led to a sharp increase in China's population, but there is no specific and effective bill to limit the population growth, which led to a sharp increase in the population. Moreover, due to the imperfect economic development and social welfare, the problems of old-age care and medical care in developing countries in Asia deserve the attention of the elderly, which makes old-age care necessary and makes every family have at least one child, which is rare under the sound welfare system in the United States.

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