The historical trend shows that if at the beginning of the 20th century, the growth rates of the US population were much higher than in all European countries, then over the century their decline began to gain momentum, which after 1960 manifested itself not only relatively, but also absolutely.
The rate of change in the US population is determined by three factors: the birth rate (the number of births per 1000 people – per thousand), the mortality rate (the number of deaths per 1000 people) and the amount of net migration (calculated as the difference between the number of immigrants who entered the country and those who left the country – emigrants for a certain period of time). For a hundred years (from 1900 to 2000), net migration to the United States amounted to 40 million people, the total birth rate reached 330 million, the number of deaths totals 165 million people3. From 2000 to 2009, net migration amounted to 8.9 million people, total fertility – 38.4 million, mortality – 22.5 million4. The share of these indicators in the increase / decrease in the population size varies from decade to decade.