US President Donald Trump has extended a pause on some green cards and suspended visas for other foreign workers until the end of 2020.
High-skilled tech workers, non-agricultural seasonal helpers, au pairs and top executives will be affected.
The White House said the move will create jobs for Americans hurting economically due to the pandemic.
But critics say the White House is exploiting the coronavirus pandemic to tighten up immigration laws.
In a briefing for reporters, the administration said the freeze, in place through the end of the year, would impact about 525,000 people.
That includes an estimated 170,000 people blocked by the decision to extend a ban on some new green cards – which grants permanent residence to foreigners. The White House first announced it was halting those visas in April, an order that had been set to expire on Monday.