It's a day of celebration for travelers and airlines.

The U.S. reopened its borders to international flights on Monday (November 8).

That's sparked festivities at hubs including London's Heathrow Airport, and a jubilant mood among travelers headed for long-awaited trips and family reunions.

"Excited. It's been a long time."

"It's just amazing, isn't it?"

"Yeah, it's been a long time waiting to find out."

Restrictions have been in place for almost two years.

The U.S. barred access from 33 countries, including China, India, and much of Europe.

In the coming weeks there are now expected to be few if any empty seats on flights to the U.S. from London, Paris, and elsewhere.

That comes as relief to airlines, especially those flying across the Atlantic, which is a key route for many.

In the six weeks since the reopening was announced, U.S. carrier Delta says it's seen a 450% increase in international bookings.

Though experts say the lucrative business travel market may take some time to rebound.

Shai Weiss is boss of UK airline Virgin Atlantic:

"Yes, flights are filling up quite nicely. About 45% of the bookings are for November and December but we're already seeing Easter and the summer is starting to pick up. Now we're not at 2019 levels and don't expect to be that. But for Virgin Atlantic, will be at full capacity in terms of seats and flights by April 2022."

Air travelers will still have to show official proof of vaccination and a recent negative virus test.

Do that, and the long wait for U.S. travel is finally over.