At least 700,000. The top estimate is 1 million.
(1) Government, universities, and non-profit research labs have no H-1B quota and no reporting requirements, so no one knows the true number.
(2) Also, once an employer sponsors a H-1B for a Green Card, there is no quota and no reporting requirement.
(3) The “Optional Practical Training” (OPT) program is the new backdoor H-1B. This program is included on a standard foreign student visa. Foreign STEM graduates can work in the USA for up to 36 months. They compete directly against USA born graduates. Because the OPT renews each year, it is not clear how many OPTs are in the USA. Best estimate - 300,000.
We should not have a problem with those coming here on H1B visas. They are normally educated and work hard.
Everyone’s ancestors originally came here from somewhere else.
Illegal immigration is what needs to be stopprd.
Build the wall.