There is no easy way to estimate the net change from year to year in foreign workers coming to the U.S. and the number of foreign workers in the U.S. at any time. The following figures can help. One can infer from these figures that upwards of half of the net increase in foreign workers has been illegal workers. The entire set is divided among official permanent admissions, official temporary admissions, and illegal entrants.
Number of foreign-born persons in the U.S. today: 35 million
Subset of 35M who have become American citizens: 12 million
Subset of 35M who are eligible for citizenship but have elected to become citizens as yet: 8 million
Simple math suggests that about 15 million foreign born people in the U.S. are neither citizens nor on a citizen track. The estimated 12 million illegal immigrants make up the large majority of these persons.
OFFICIAL PERMANENT ADMISSIONS
Number of persons (adults, children, retirees) formally admitted into the U.S. each year for permanent residence (which can lead to citizenship): roughly about 1 million
(This and other official figures below are rough due to volatility from year to year, driven in part by paperwork backlogs)
Subset of these 1M persons who are working age adults: 400,000?
Subset of these 400,000 +/- working age adults who were admitted on the basis of employment criteria (“employment based preferences”) as opposed to family ties, other: about 150,000
OFFICIAL TEMPORARY WORK ADMISSIONS
Number of new H-1B temporary professional workers formally admitted each year (i.e. Bill Gate’s programmers): 95,000
Number of new H-2A temporary agricultural workers (special agricultural workers) admitted each year: 200,000? less those returning
Number of other temporary workers admitted for miscellaneous programs: to be found but probably well under 50,000 (types: H-2B, H-1C, E, L, O, P, R, for nurses, ministers, ahtletes, etc, etc.)
ILLEGAL ENTRANTS
Number of new illegal workers each year: roughly 350,000