What is the main reason for the growth of the US population?

Population growth in the United States is mainly due to migration growth, the main flows are as follows:

From Europe. Historically, most of the migrants came from there, who made up the backbone of the country (Anglo-Saxons, Celts, Germans, French, Spaniards), in the 21st century the flow has decreased, but citizens of former socialist countries, for example, Albania and Poland, are still coming.
From Asia. In the United States, residents of almost all Asian countries are represented, from Japanese to Filipinos, to Jews and Arabs.
From Africa. Ethiopians, Arabs and other peoples.
From South America, residents of almost all countries are also represented. including the poorest, such as the Haitian community in New Orleans.