Which continent do American immigrants mainly come from? Which continent?

Mainly in Europe and America, but also in Asia, for the following reasons:

The core reason of European immigration is that the collapse of European feudal system has led to a large number of farmers and craftsmen;

The reason for African immigration is the sharp decline of native Americans, and a large number of European slave traders sell slaves from Africa to America.

The reasons for Asian immigration are similar to those in Europe, all of which are the bankruptcy of feudal natural economy.