When the U.S. closed its airspace after the September 11 attacks, Gander International Airport took in 38 commercial aircraft and four military aircraft, and accommodated nearly 6,700 passengers from airlines

https://en.wikipedia.org/wiki/Gander,_Newfoundland_and_Labrador

Every transatlantic flight had to land when the US closed their airspace.

Newfoundland is an island in the middle of the Atlantic and prior to the 1970s the only way to fly to Europe was to stop in Newfoundland to refuel. As a result Gander has a giant airport that now sits idle.

On 9/11 it became a hub for flights because of the number and size of the runways. The town only has a few thousand people and very few hotels. So the town more than doubled overnight. So the people took strangers into their homes and looked after them for weeks until they go back to where they came from.

On a side note nobody knew how many planes were weaponized. Canada agreed to take the risk and allowed those planes to use our airports to protect the US.

I haven’t looked this up so might be completely misremembering: I think they basically like homestayed a bunch of stranded international travelers after NA airspace got locked down for 4 days.