What is the largest portion of immigrants in Mexico?

Americans qualify as such. Nowadays, between 800,000 and 1,000,000 registered immigrants can trace their origin to the United States. They are followed by immigrants from Guatemala (35,000), Spain (20,000) and Colombia (14,000).

As Mexico does not include ancestry within its population census, it is impossible to determine the number of American-Mexicans or people from foreign ancestry within its population.