Authorities on both sides of the border have eased strict security measures, which were hurriedly introduced after the discovery of an alleged plot to blow up trans-Atlantic airliners using liquefied explosives in August.
Total bans on liquids, gels and aerosols in hand baggage were imposed after Britain foiled the plot.
But the US Transportation Security Administration (TSA) warned the "orange" or "high" alert level for aviation would stay in force, and warned liquid explosives were still part of the terrorist “playbook."
Liquids limited
Passengers boarding domestic and international flights at US airports will be able to take travel-sized toiletries like shampoo or toothpaste through security in containers smaller than 100 millilitre.
The items must be held in a clear, zip-top plastic bag.
Passengers will also be permitted to buy items including beverages and duty-free items in new "sterile" areas of the airport after passing through security.
But the TSA said the ban on other items, like soft drink cans, bottles of water, and perfumes in larger containers originating from outside airports, would stay in place.
"We are keeping the current arrangements in place for an indefinite period of time," said Kip Hawley, assistant secretary of the TSA.
"After the initial total ban, we have learned enough from the UK investigation to say that small travel-sized liquids are safe to bring through security check points in limited numbers."
The 100 millilitre limit was "well within the comfort zone of what we need to protect the public," said Hawley, but warned liquid explosives were "still an ongoing part of the terrorists' playbook."
He declined to say what quantity of liquid explosive would pose a threat, but said authorities were confident that potential terrorists would not be able to combine liquids held in small containers to fashion a bomb.
EU follows suit
The foiling of the alleged plot in London triggered unprecedented security -- and travel chaos -- at major airports across the world.
Two weeks ago, the European Commission said it would permanently restrict the amount of liquids carried in hand luggage, while ruling out a total ban.
Maximum container sizes will be introduced under the new EU rules, allowing people to bring on board small shampoo and perfume bottles. Duty free airport purchases will be carried in sealed bags.