The first recreational cannabis to be legally bought in Canada was purchased at midnight on Wednesday (02:30 GMT) on the eastern island of Newfoundland amid queues of hundreds of people.
Canada has become the second country after Uruguay to legalise possession and use of recreational cannabis.
Medical marijuana has been legal in the country since 2001.
But concerns remain, including about the readiness for police forces to tackle drug impaired driving.
Information has been sent to 15m households about the new laws and there are public awareness campaigns.
Ian Power, from the town of St John’s began queuing at 20:00 local time so he could “make history”. Newfoundland is half an hour ahead of the next province to the west.
“It’s been my dream to be the first person to buy the first legal gram of cannabis in Canada, and here I finally am,” he said.
Canadian provinces and municipalities have been preparing for months for the end of cannabis prohibition. They are responsible for setting out where cannabis can be bought and consumed.
This has created a patchwork of more or less restrictive legislation across the country.
How ready is Canada for legal cannabis?
There remain unanswered questions on some key issues around how legal cannabis will work in Canada.
A number of analysts are predicting a shortage of recreational marijuana in the first year of legalisation as production and licensing continues to ramp up to meet demand.
And the marketplace itself is still in its infancy.
Ontario, Canada’s most populous province, will only begin opening retail stores next spring, though residents will be able to order cannabis online.
British Columbia, one of the provinces with the highest rates of cannabis use, will only have one legal store open on Wednesday.
Until retail locations are more widely available, some unlicensed cannabis retailers, which have flourished in the years since the law was first proposed, may stay open.
It is unclear if police will crack down on them immediately, or if they will turn a blind eye.