Pot-store proprietors in Washington state have a blunt warning for their Canadian customers on the first day of legal marijuana sales.

"Don't take it home," says Aaron Nelson, the senior vice-president of operations at 2020 Solutions, a pot vendor that will be open for business Tuesday in Bellingham, Wash. "We are eager to see our customers from across the border. We just want to make sure they understand that the products are for consumption in the state of Washington."

The state's Liquor Control Board issued 24 retail marijuana licences on Monday, a development 20 months in the making after both Washington and Colorado voted in November, 2012, to legalize pot for adults over 21.

Story continues below advertisement

Colorado kicked off sales on Jan. 1.

Many of Washington state's newly minted pot emporiums are expected to run out of product shortly after opening their doors Tuesday morning, because of a shortage of legally produced marijuana in the state. High prices and celebrations are also expected.

Mr. Nelson said he has gotten a number of calls from excited Canadians – mostly from Vancouver – who are planning to cross the border to see "history being made." The owners of Top Shelf Cannabis in Bellingham and Cannabis City in Seattle also said they're expecting Canadian customers.

Meanwhile, the Canada Border Services Agency and U.S. Customs and Border Protection are making an effort to remind travellers that smuggling drugs across the border is still a crime.

"CBSA officers are mandated to enforce Canadian laws and regulations at our ports of entry and are committed to preventing illegal narcotics from entering into Canada," the Canadian agency said in a statement.

"Changes to American laws do not affect the CBSA's mandate. In Canada, the possession of cannabis is illegal, and it is a criminal offence to import illegal drugs, including cannabis, into Canada."

U.S. Customs and Border Protection echoed the warning, adding a strongly worded caution that being found guilty of violating a federal or state law related to controlled substances could result in being barred from entering the U.S. in the future.

Story continues below advertisement

"In enacting the Controlled Substances Act, Congress determined that marijuana is a Schedule I controlled substance and CBP's enforcement of that Act remains unchanged irrespective of any changes in Washington State law," the agency said in a statement.

As Washington state's marijuana shops were gearing up for business, Canada's "prince of pot" was preparing to be freed from a U.S. prison.

Marc Emery, now 56, was extradited to Seattle in May, 2010, and pleaded guilty to selling marijuana seeds from Canada to American customers before serving his time in several U.S. jails.

His wife, Jodie Emery, said Mr. Emery's sentence ends Wednesday, but it could be several weeks before he can celebrate his freedom. Mr. Emery will be transported to a private deportation facility, where he'll wait for a flight to Detroit and then a transfer across the border.

With reports from The Canadian Press and The Associated Press.