Yerin Hong gets a hug from her boyfriend Soomin Kim after she arrived on a flight from Germany at the international terminal at O'Hare International Airport in Chicago, Illinois.

Yerin Hong gets a hug from her boyfriend Soomin Kim after she arrived on a flight from Germany at the international terminal at O'Hare International Airport in Chicago, Illinois. / Getty Images

The U.S. reopened on Monday to fully vaccinated international travelers from 33 countries including Mexico, Canada and most of Europe. Travelers reconeccted with loved ones at airports and border crossings. Proof of vaccination and a negative COVID-19 test is required for air travel and those entering from Mexico and Canada's land borders only require proof of vaccination.

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Cars line up to enter the U.S. from Canada at the Peace Arch border crossing in Blaine, Wash.

Cars line up to enter the U.S. from Canada at the Peace Arch border crossing in Blaine, Wash. / AP

Dual U.S.-Canadian citizen Traysi Spring, right, and her American husband Tom Bakken, hold a homemade sign to welcome people heading into the U.S. from Canada on Monday.

Dual U.S.-Canadian citizen Traysi Spring, right, and her American husband Tom Bakken, hold a homemade sign to welcome people heading into the U.S. from Canada on Monday. / AP

A couple embrace each other as they are reunited upon her arrival on a flight from Frankfurt, Germany.

A couple embrace each other as they are reunited upon her arrival on a flight from Frankfurt, Germany. / AFP via Getty Images

A pedestrian walks past a line of Canadian travelers in their passenger cars or motor homes on the Rainbow Bridge between Niagara Falls, Ontario and Niagara Falls, New York in the early hours of November 8, 2021.

A pedestrian walks past a line of Canadian travelers in their passenger cars or motor homes on the Rainbow Bridge between Niagara Falls, Ontario and Niagara Falls, New York in the early hours of November 8, 2021. / AFP via Getty Images

Passengers walk past airline staff as part of a welcoming event after arriving on a flight from the UK, following the easing of pandemic travel restrictions at JFK international airport in New York.

Passengers walk past airline staff as part of a welcoming event after arriving on a flight from the UK, following the easing of pandemic travel restrictions at JFK international airport in New York. / AFP via Getty Images

Alison Henry embraces her son Liam as they meet after arriving on a flight from the UK.

Alison Henry embraces her son Liam as they meet after arriving on a flight from the UK. / AFP via Getty Images

A Lufthansa Crew in traditional Bavarian costume wave to an Lufthansa Airbus A 350-900 prior to a flight bound non-stop for Miami at Munich Airport on the first day that U.S. authorities are allowing tourists from Europe to enter the U.S.

A Lufthansa Crew in traditional Bavarian costume wave to an Lufthansa Airbus A 350-900 prior to a flight bound non-stop for Miami at Munich Airport on the first day that U.S. authorities are allowing tourists from Europe to enter the U.S. / Getty Images

Natalia Abrahao is lifted up by her fiancé Mark Ogertsehnig as they greet one another at Newark Liberty International Airport in Newark, N.J.

Natalia Abrahao is lifted up by her fiancé Mark Ogertsehnig as they greet one another at Newark Liberty International Airport in Newark, N.J. / AP

Mexican immigration officials greet motorists at the Mexico-U.S.border at the San Ysidro Port of Entry in Tijuana, Mexico.

Mexican immigration officials greet motorists at the Mexico-U.S.border at the San Ysidro Port of Entry in Tijuana, Mexico. / Getty Images

U.S. Customs agents check vaccination cards at the San Ysidro Port of Entry.

U.S. Customs agents check vaccination cards at the San Ysidro Port of Entry. / Getty Images

Cars line up at the Paso del Norte international bridge in Ciudad Juarez, Mexico, below, on the border with El Paso, Texas on Monday.

Cars line up at the Paso del Norte international bridge in Ciudad Juarez, Mexico, below, on the border with El Paso, Texas on Monday. / AP

Performers entertain passengers at London Heathrow Airport's T3 as the U.S. reopens its borders to UK visitors in a significant boost to the travel sector.

Performers entertain passengers at London Heathrow Airport's T3 as the U.S. reopens its borders to UK visitors in a significant boost to the travel sector. / PA Images via Getty Images