Saskatchewan doesn't just export oil, grain, farm equipment and potash.

Since the commodity downturn, people have once again become one of Saskatchewan's exports.

"The province has not been a large net gainer over the long haul," said Rose Olfert, an economics professor at the Johnson Shoyama Graduate School of Public Policy at the University of Saskatchewan.

She's spent four decades analyzing Saskatchewan's population trends.

The province's population has 'been hovering around a million people ever since 1936,' said Rose Olfert, an economics professor who's spent more than 40 years studying Saskatchewan's economy and demographics. (Johnson Shoyama Graduate School of Public Policy)

Rising birth rates and immigration pushed Saskatchewan's population up by more than 141,000 people over the past two decades, according to Statistics Canada, which released new data on interprovincial migration on Tuesday.

In 2015-16 — the latest year for which Statistics Canada provided data — Saskatchewan tied with Manitoba for the lowest net interprovincial migratory rates among the provinces, the agency said. Saskatchewan had a net loss of 3.7 people per 1,000 population, according to Statistics Canada.

By comparison, B.C. had a net gain of 5.6 people per 1,000 population and Ontario a net gain of 0.7 people per 1,000 in 2015-16, Statistics Canada said.

"A lot of those migrants who came to Saskatchewan during the boom years were fairly young people in the labour force and they also had more children," said Olfert, who said that's pushed population figures up since about 2009.

Statistics Canada also showed that the year Brad Wall was elected premier, 4,171 people moved from other provinces into Saskatchewan.

​But commodities and natural resource prices move in cycles. When the downturn began in 2014, Saskatchewan resumed its long-term trend of losing people to other provinces.

"In Saskatchewan we have a very, very mobile labour force, a very efficient labour force," said Olfert, noting people move primarily for work. "That's not necessarily a bad thing."

She noted Saskatchewan's Immigrant Nominee Program requires new Canadians to stay in the province for a given length of time.

But last year was the first year Saskatchewan did not bring in enough newcomers to balance out the exodus to other provinces, according to data from the Government of Saskatchewan.

"Just because they come here doesn't mean they stay here," said Olfert.

"I think that's another part of immigration policy that will be really important," she said. "Can these people find not only jobs, but can they find a community here and a lifestyle that they are happy with and are they content to stay in Saskatchewan?"

Eighty years ago, archives show the province reached a population of 931,547. It's hovered around the one million mark ever since.

Olfert said that's partly because people in Saskatchewan are mobile, and tend to move where the jobs are.

"If we have a bust in our economy and people find jobs in other provinces, that's exactly what should happen. They shouldn't stay here to be unemployed," she said.