Canada has become the second country after Uruguay to legalise possession and use of recreational cannabis.
The nationwide market for cannabis opened on Wednesday at midnight amid lingering questions about the impact on health, the law and public safety.
Information has been sent to 15m households about the new laws and public awareness campaigns.
But there remain concerns, including about the readiness for police forces to tackle drug impaired driving.
Uruguay was the first country to legalise recreational marijuana, although Portugal and the Netherlands have decriminalised the drug.
Canadian provinces and municipalities have been preparing for months for the end of cannabis prohibition.
Provinces and territories are responsible for setting out many of the details for where cannabis can be bought and consumed within their jurisdictions.
This has created a patchwork of legislation across the country as jurisdictions choose more or less restrictive frameworks for selling and using cannabis.
Shops in the province of Newfoundland, the most easterly time zone in Canada, opened as midnight struck for the first legal sales of cannabis in the country.
How ready is Canada for 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.
What are the new rules around cannabis?
Adults will be able buy cannabis oil, seeds and plants and dried cannabis from licensed producers and retailers and to possess up to 30 grams (one ounce) of dried cannabis in public, or its equivalent.
Edibles, or cannabis-infused foods, will not be immediately available for purchase but will be within a year of the bill coming into force.
The delay is meant to give the government time to set out regulations specific to those products.
It will be illegal to possess more than 30 grams in public, grow more than four plants per household and to buy from an unlicensed dealer.
Penalties for some infraction will be severe. Someone caught selling the drug to a minor could be jailed for up to 14 years.
Some critics say the penalties are too harsh and not proportional to similar laws like those around selling alcohol to minors.