Canada has posted signage at airports and boarder crossings to keep recreational cannabis users aware - crossing worldwide boarders with the drug is still very much illegal.
The start of legal sales wasn't the only good news for pot aficionados: Canada said it intends to pardon everyone with convictions for possessing up to 30 grams of marijuana, the newly legal threshold.
Jubilant customers stood in long lines for hours then lit up and celebrated on sidewalks as Canada became the world's largest legal marijuana marketplace.
"Marijuana is illegal federally in the US, so use of, sales or production, or distribution could render someone admissible to the United States", said Charles Perry, CBP director of field operations.
Although Uruguay started selling cannabis products past year under a 2013 law, Canada's foray is considered more significant because of its economic status and much larger population.
"Federal law supersedes state law", he said.
A depiction of a cannabis bud hangs from the ceiling as a band plays at Leafly's countdown party in Toronto, Tuesday, Oct. 16, 2018, as they prepare to mark the legalization of Cannabis across Canada. It is up to the border agent's discretion.
Trautman expects less potential crossing problems between Canadian provinces and states where cannabis is clearly illegal.
Elsewhere in the world, Georgian and South African high courts issued rulings earlier this year that legalized personal use of marijuana without legalizing sales.
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Canada's legalization has left proponents in the USA calling for Congress to act. Sen.
Media officer Josh Fraser said this specialty training is only offered in the USA and it's been a challenge to get officers enrolled, as spots are limited. "Canadian legalization will proceed with very little impact on the United States". Several medical marijuana producers are already on Canadian stock markets. "You're better off sticking with the domestic product".
Still, worldwide businesses and investment funds have been hovering around the market for years, waiting for the time when they could legally invest in large-scale industrializing marijuana cultivation and distribution.
Prime Minister Justin Trudeau has defended legalisation - the fulfilment of a 2015 campaign promise - as meant to protect young people and to shut down drug dealers. The pledge was aimed at taking profits away from organised crime and regulating the production, distribution and consumption of a product that millions of Canadians consume illegally.
According to the federal government, there could be as many as 300 storefronts across Canada selling cannabis by year's end.
"The cartels will always be many steps ahead of the provincial and federal bureaucrats unfortunately, I hate to say it", Sabet said.
Canada legalised medical marijuana in 2001, and many in the industry spent the last days of prohibition completing displays, holding mock openings and training employees to use sales-tracking software.
Thousands of Canadians lined up in front of over 100 private and government stores Wednesday, including Corey Stone, who arrived just before 4 a.m.at a government store in downtown Montreal. "By giving adults a regulated legal alternative we believe we can make our communities safer".
The ability of the legal market to displace the black market rests heavily on price - an analysis conducted by the consulting firm Deloitte pre-legalization put the average price of illegal weed at $8.24 across Canada.