The US has suspended all non-essential traffic across its borders with both Mexico and Canada as it battles to control the coronavirus outbreak.
The curbs will go into effect at midnight on Saturday but will not affect trade, Secretary of State Mike Pompeo said on Friday.
Meanwhile New York State order has told non-essential businesses to close, a day after a similar move by California.
Countries around the world are stepping up restrictions to combat the virus.
The virus has claimed more than 220 lives in the US and infected more than 16,000 people.
Globally nearly 250,000 patients have tested positive for the respiratory illness and more than 10,000 have died.
On Wednesday President Trump announced that the border with Canada would be closed to non-essential traffic “by mutual consent”.
During Friday’s news briefing he said the Mexican border would be sealed off to “unscreened” travellers.
Acting Homeland Security Secretary Chad Wolf said the US was “working with both our Canadian partners as well as our Mexican partners” to limit “non-essential travel”.
He added: “We want to make sure cargo continues, trade continues, healthcare workers continue to be able to traverse that border. But tourism, some recreational activities and other things need to stop during this crisis.”
The restrictions are due be in place for at least 30 days.
Mr Pompeo said US citizens “should arrange immediate return” unless they intend to remain abroad for a time. “If you choose to travel, it may well be fairly disruptive,” he said.
Image credit: Reuters