The first population counts from the 2016 census will be released Wednesday and they're expected to show that Canada continues to grow at a steady clip, fuelled primarily by immigration. It's also tilting ever more to the West, as Alberta continues to boom and Quebec and Atlantic Canada see their relative share of population decline.

Those trends encapsulate a few issues of central importance to the federation: the place of Quebec, the rise and fall of the regions, and the role of immigration. But in an age when facts are increasingly contested, no one debates whether they're real or not. In part, that's due to public faith in the census.

But the seemingly benign act of counting and sorting the population can often be politically sensitive. Canada got a taste of that in the angry outcry over the termination of the mandatory long-form census in 2011.

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Censuses, which date back to antiquity, usually had either taxation or military conscription at their root. The first recorded census in what would become Canada began in 1665 by Jean Talon, who gathered much of the data himself by going door-to-door. He found that men outnumbered women by nearly two to one in the colony.

In the 19th century, a new passion for counting things coincided with the rise of nation states, and a properly conducted census was seen as essential to projecting a positive image abroad, and to uniting a population around the relatively new concept of nationhood.

Bruce Curtis, a professor at Carleton University and author of The Politics of Population, said the first radical assumption embedded in the census is the idea that every person counts as one, the same as every other person.

"In most historical periods the notion that everybody is fundamentally the same is just completely incomprehensible. In medieval Europe to say that a serf and a lord are the same is nonsense, like saying a dog is a horse," Prof. Curtis said.

In the United States, where the census determined representation in congress, there was fierce debate about how slaves should be counted. It was settled by a compromise in which slaves were counted as three-fifths of a person until the civil war. In some countries to this day taking a census is almost too divisive to contemplate. Lebanon, for example, hasn't held one since the 1930s.

In Canada, political tensions have revolved primarily around the size of the population and the balance of power between French and English. The first censuses after the union of Upper and Lower Canada were "incredibly haphazard," according to Prof. Curtis, with "double counting going on all over the place." Inflating the count was useful for a government aiming to attract immigrants and investors by showing that Canada was a prosperous and rapidly growing country.

"The census ends up being first of all an advertising exercise," Prof. Curtis said. "So there's an interest not in making a precise count of population but in making a count that shows as much population as possible."

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Canada's first post-Confederation census in 1871 was led by Joseph-Charles Taché. He's credited with ushering in much more rigorous methods, but he was also, according to Prof. Curtis, an ultramontane Catholic fundamentalist with his own interest in obtaining certain results. Prof. Curtis argues that Mr. Taché, who also led the 1881 census, inflated the population of Quebec by allowing people to be counted at their "family of origin." At a time when a large chunk of its population had actually migrated to the cities, to the West and to the factories of New England, rural Quebec got an artificial population boost.

"He wants to show that the French Canadian population is the most flourishing and fastest growing population in the world," Prof. Curtis said.

Since the interest was in inflating the population generally, indigenous people were always counted in Canada, but the counting was usually done by Indian agents, and some indigenous people by the late 19th century were suspicious of government's intentions in gathering data, according to Peter Baskerville, a University of Alberta historian.

Over the years the census has provided a reflection of society even at the level of the questions it asks. To take one example, the 1931 census asked whether there was a radio set in the home, a question that's no longer asked today. And one of the features of Canada's census is that census takers have been open to discussing what questions should be asked. For example as far back as 1891 pressure from labour groups led to a question about the labour force, according to Prof. Baskerville, which they likely intended to use as a tool to push for better wages.

"The nation has benefited from the process of census taking as it has unfolded. It allows various groups in society to better understand themselves, it allows groups to gain power from that understanding in terms of pressuring for change," Prof. Baskerville said.

Doug Norris, a former census director who now works at Environics Analytics, said he expects this year's data will show growth of about 1 per cent a year in population, with gains in Alberta and other parts of the West, and only small growth in Quebec and Atlantic Canada.

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Marc Hamel, director general of the census program at Statistics Canada, said he thinks of the census as a family portrait.

"It's basically a reflection of who we are and how we're changing," Mr. Hamel said.

This year census data will be released more quickly than in years past, as all the data from the long-form census will be out before the end of 2017, about 10 months sooner than last time. It will also be under budget, according to Mr. Hamel. The census was budgeted to cost $715-million over a seven-year planning cycle, but the agency expects to return between $35-million and $45-million to the Treasury.

Much of that saving is due to the efficiency of the process, as more than 68 per cent of people responded online, and nearly 90 per cent didn't need help or need to be chased down to respond.

The long-form response rate was nearly 98 per cent nationally, much higher than the 68 per cent for the voluntary household survey in 2011.