Hundreds of passengers were left waiting for hours at JFK airport in New York yesterday when three planes from the UK arrived at the same time.
The US border re-opened to British travellers for the first time in 604 days or nearly 20 months.
One traveller took to social media to share a video of long lines and blasting officials for "disgraceful" planning.
It showed long queues snaking around the arrivals hall as hundreds wait to be let into the US.
America is expecting a flood of international visitors crossing its borders by air and by land on Monday after lifting travel restrictions for much of the world's population first imposed in early 2020 to address the spread of Covid-19.
More than 10,000 passengers flew from London to New York City yesterday.
British Airways took 8,600 travellers on 26 planes while Virgin Atlantic brought a further 4,500 customers on 10 flights shuttles into JFK.
One Twitter user shared a video of the backlog of traffic and blamed three planes landing at once.
He wrote: "20 months closed lots of time to get things right and JFK Airport queues are a disgrace, three planes landing at the same time from Manchester is ridiculous."
Asked how long he had been waiting, he added: "Two hours mate, pathetic. We were all sweating. Just approaching Manhattan now."
Paul Richards, 58, who is head of safeguarding for Stoke City FC, also said he waited two hours after his Virgin Atlantic flight from London.
He told USA Today : "No point in getting irate, the queue will still be there."
Policeman Marc Evans, 42, who flew from Manchester, with his wife and two children said he waited more than an hour.
He said: "It was apparently a PR stunt to show the USA was back open but seems they weren't concerned about the queues at customs."
Another wrote on Twitter: "Great. Queues are JFK are bad enough without two planes touching down at the same time."
Delta Air Lines Chief Executive Ed Bastian had earlier said: "It's going to be a bit sloppy at first. I can assure you, there will be lines, unfortunately.
He added: "We'll get it sorted out."
Heathrow Airport also received numerous complaints on social media for long queues.
One wrote on Twitter: "Beside myself with appalling service of @BritishAirwaysT trying to get my lovely mum on a flight! @HeathrowAirport waiting 2 hours now!"
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She added: "She's gone through security. But we are both in tears… this is not a good experience!"
Another wrote: "@HeathrowAirport someone needs to inform your airport assistance personnel that a long connection is nice license to leave a customer sitting and waiting."
Yesterday was an emotional day for many as Britons were reunited with friends and family for the first time in 20 months.
Heartwarming images showed couples and families embracing for the first time in nearly two years.
Currently, Brits need to be fully vaccinated against Covid if they want to visit the US for non-essential reasons, such as a holiday.
You'll need to be able to show proof of full vaccination such as the AstraZeneca, BIBP/Sinopharm, Covishield, Janssen, Moderna, Pfizer-BioNTech and Sinovac vaccines.
You'll also need to show proof of a negative Covid PCR test result taken within 72 hours before departure, and face masks are mandatory in planes travelling into/within/out of the USA, as well as airports.
Children under 18 are exempt from the vaccine requirements, but they will need to take a test within 3-5 days of arrival (and self-isolate if they develop symptoms or test positive).
Travel rules are correct at the time of writing but can change quickly during the pandemic, so before planning a trip make sure to always check the Foreign Office's latest USA travel advice. You can also get more information on the US government website.
If you're not fully vaccinated against Covid, you'll need an essential reason to travel to the USA. If you meet the criteria, you'll need to self-isolate for your first seven days after arrival, and also take a test within 3-5 days of arrival.
