The United States reopens its land and air borders Monday to foreign visitors fully vaccinated against COVID-19, ending 20 months of restrictions on travel from around the globe that separated families, hobbled tourism, and strained diplomatic ties.

The ban, imposed by former President Donald Trump in early 2020 and upheld by his successor, Joe Biden, has been widely criticized and become emblematic of the upheavals caused by the pandemic.

The restrictions were particularly unpopular in Europe and U.S. neighbors Canada and Mexico.

In an effort to slow the spread of the coronavirus, U.S. borders were closed after March 2020 to travelers from large parts of the world, including the European Union, Britain, and China, India, and Brazil. Overland visitors from Mexico and Canada were also banned.

The months of restrictions affecting hundreds of millions of people helped fuel both personal and economic suffering brought on by the COVID-19 pandemic.

“It’s been so hard,” Alison Henry, 63, said. “I just want to see my son.”

The British woman plans to fly Monday to see her son in New York, after 20 months of separation.

Families on both sides of the Atlantic are eager to reunite with their loved ones.

Although travel from the United States to Europe has been possible since the summer, foreign U.S. residents holding certain visas have had no guarantee of re-entry.

To cope with surging demand, airlines have increased the number of trans-Atlantic flights and plan to use larger planes, as they work their way out of the pandemic crisis.

Along the border with Mexico, many cities in the U.S. states of Texas and California have faced economic struggles due to anti-COVID trade restrictions.

Authorities in Mexican border cities warned Sunday there would be long lines at crossings. The reopening also caused a shortage of dollars in currency exchange centers in Ciudad Juarez.

The Ciudad Juarez government has implemented a special system to direct traffic, including installing portable toilets on the three bridges crossing into the United States “as waiting times of up to four hours are estimated,” said the local director of road safety, Cesar Alberto Tapia.

In the United States’ northern neighbor, seniors will be able to resume their annual trips to Florida to escape the bitter Canadian winters.

But the cost of PCR tests Canada requires for cross-border travel — up to $250 — can be prohibitive.

Ann Patchett, an Ontario resident, told the Ottawa Citizen it will cost $500 for her and her husband to go south to visit family.

“Do you want to hug your children? Do you want to tuck your grandchildren into bed?” she asked. “It’s very frustrating.”

New York Rep. Brian Higgins, whose district touches the Canadian border and includes the U.S. side of Niagara Falls, plans to hold a news conference Monday with mayors from both countries to urge Canada to drop its testing requirement.

Lifting the travel ban will affect more than 30 countries, but entry into the United States will not be totally unregulated: U.S. authorities plan to closely monitor travelers’ vaccination status and will still require them to present negative COVID-19 tests.

The United States, from Monday, will require air passengers to be fully vaccinated and be tested within three days before travel. Airlines will be required to put in place a contact tracing system.

The land border opening will happen in two phases.

Starting Monday, vaccines will be required for “non-essential” trips — such as family visits or tourism — although unvaccinated travelers will still be allowed into the country for “essential” trips, as they have been for the last year and a half.

A second phase, beginning in early January, will require all visitors to be fully vaccinated to enter the United States by land, no matter the reason for their trip.

U.S. health authorities have said all vaccines approved by the U.S. Food and Drug Administration and the World Health Organization would be accepted for entry by air.

Washington has not yet commented on Europe’s recent COVID-19 case increase.

The WHO has expressed “grave concern” over the rising pace of infections in Europe, warning the current trajectory could mean “another half a million COVID-19 deaths” by February.

U.S. Surgeon General Vivek Murthy said Sunday on ABC he’s “cautiously optimistic about where we are,” while adding: “We can’t take our foot off the accelerator until we’re at the finish line.”

But in Berlin, 51-year-old Elisabeth Zours is ready to hit the road.

A lifelong Rolling Stones fan, Zours had to miss a St. Louis show by the rock supergroup in September due to COVID-19 restrictions and was “frustrated” by the slow U.S. reopening.

Now she plans to make up for the lost time.

“I’ve got tickets for four (U.S.) concerts,” she said.