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Prime Minister Mark Carney speaks alongside Alberta Premier Danielle Smith in Fort McMurray. Alta., earlier this month. The Prime Minister is pushing for the province to remain in Canada ahead of a vote on separation next week.Greg Halinda/The Canadian Press

Prime Minister Mark Carney is making the case for a united Canada as Albertans prepare to vote in a referendum on the province’s place in Confederation.

In a video posted online on Monday, Mr. Carney said Albertans helped build Canada, and he raised concerns about uncertainty linked to the sovereignty vote.

“A week from today, Albertans will have the opportunity to make an important decision about their future – whether to remain part of Canada or begin a long and uncertain process through which Alberta could separate from Canada,” Mr. Carney said in the video timed to the Thanksgiving holiday.

Mr. Carney filmed the video a classroom at St. Francis Xavier High School in Edmonton, which he attended as a student.

Mr. Carney talked about his government’s record in the province, citing federal support for building new homes, high-speed rail and a new pipeline to the West Coast.

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But he said Canada can’t build big things if it is divided, and that the country is facing threats to its economy, security and way of life.

“We are stronger together. Generations of Albertans helped build this country. It’s yours. It’s ours. And it’s worth fighting for.”

Advance voting opens Tuesday in the referendum, with a vote to follow on Oct. 19 on 10 questions that include whether the province should stay in Canada or hold a second, binding referendum on leaving the country.

Mr. Carney will be in Alberta this week to make the case for remaining in Canada. Conservative Leader Pierre Poilievre and other leaders are also scheduled to speak in the province.

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Alberta Premier Danielle Smith launched the referendum process, saying it was necessary to allow Albertans to resolve the question of the province’s place in Canada.

Ms. Smith has said she supports Alberta remaining a part of Canada.

On Sunday, Ms. Smith’s press secretary, Sam Blackett, said Alberta’s government will continue its advertising campaign urging Albertans to vote in support of a strong and sovereign Alberta in a united Canada.

“The Premier has been clear that our government, caucus, and party support Alberta remaining in Canada, and we will continue to work to get a strong mandate from Albertans for more sustainable immigration policies and to pursue constitutional reforms that increase our province’s sovereignty within Canada,” Mr. Blackett said.