05:01 GMT marked the reopening of the border, and the first flights left Heathrow at 08:51 GMT. To enter the US, all British visitors older than 18 must present proof of vaccination.
Americans have been able to travel to the UK since 28 July. Grant Shapps, the transport secretary, deemed this a "significant moment" for UK-US travel. He added that transatlantic flights are the lifeblood of UK aviation.
While travel continued for residents of other countries and visitors under exceptions, the ban eliminated more than half of visitors sources in the United States in 2019, according to trade group US Travel, primarily tourists and other non-essential travelers to the United States.
As well as lifting the ban on UK citizens, people from Brazil, China, India, Ireland, South Africa, Iran, and the Schengen countries - an association of 26 nations - will no longer be prohibited from traveling.
Earlier in 2020, the travel ban in the US was imposed on several major economies covering 33 countries like China, India and Europe. The ban barred access to non-US citizens traveling into the country.
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Only US citizens, residents, and a few other exempt groups were allowed entry into the US from the UK up until Monday.
All individuals who have received vaccines approved by the US Food and Drug Administration (FDA) and those listed by the World Health Organization for emergency use (EUL) are subject to the new rules.
Arriving on packed European flights or waiting in line at border crossings in Canada and Mexico, a lot of people experienced an emotional journey that ended with flowers, balloons, and homemade signs from relatives.
After months of pent-up demand, a major spike in bookings took place on Monday, with travellers only requiring proof of vaccination and a recent, negative viral test. The number of Americans booking travel for the holiday season continues to rise rapidly, according to airline and industry data.
In an early morning call with airline officials and U.S. government officials, no major issues at airports were identified, although authorities have warned about possible long queues and delays.
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The stunt was designed to highlight the importance of transatlantic trade to the UK's aviation industry. Earlier, British Airways and Virgin Atlantic flew simultaneously from parallel runways at Heathrow.
As of 8 November, foreign nationals who have been double vaccinated will be able to visit the US, White House assistant press secretary Kevin Munoz confirmed on 15 October.
"Today America is open for business. That is our message to the world," U.S. Secretary of Commerce Gina Raimondo said in an interview with Reuters at Chicago's O'Hare airport.
Additionally, seeing the holiday season, the latest data from airlines and industry shows that travel bookings in the US are growing rapidly.
Seeing the rising demand, officials have warned about potentially long queues and more delays. No major issues were raised at airports in the morning call between airlines and US government officials.
Earlier, long-term rivals British Airways and Virgin Atlantic performed a simultaneous take-off from a runway parallel to Heathrow, a stunt intended to highlight the importance of transatlantic business in the UK aviation sector.