The census is a snapshot of Canada on one particular day, May 10, 2016.

But the process of collecting the data began in early February when census takers set out to remote communities in Northern Canada that are hard to reach in spring. Some of them are at the end of ice roads, others are fly-in only. Some are on isolated islands and require booking space for a passenger on a commercial shipping vessel. Statistics Canada, through its army of 35,000 employees and contractors, sets out in search of everyone. It's a daunting task.

Read more: Census 2016: Western provinces' populations are the fastest-growing in Canada

Story continues below advertisement

"We take the means that are necessary to enumerate all Canadians and every dwelling," said Marc Hamel, director of the census program at Statistics Canada. "As you would imagine the logistics of going to these communities is quite a task. It's minus-50 [degrees] and it's dark most of the day and you try to account for the entire population."

Mr. Hamel said the agency sees many "census junkies" who come back year after year to help with the data collection.

"I'm always amazed to meet people who've done seven or eight censuses, and they're great for us because having local knowledge is very helpful. The complexity is in understanding local areas – just from a geography point of view – as you can imagine some of these areas are quite vast."

The first population counts from the 2016 census were released on Wednesday morning. The data that's gathered is the foundation for myriad decisions and processes at the heart of our system of government. It's the basis on which governments transfer billions of dollars to the local level and make decisions on hospital planning, school spending and everything from libraries and recreation centres to public transportation routes.

This time around a major hiccup arose a week before census day when the wildfires in Fort McMurray forced everyone in the city to evacuate. Mr. Hamel said the agency has contingency plans ready to go, because fires and floods are not uncommon in Canada in May. It decided to immediately suspend its collection plan for Fort McMurray, and capture the population as it was the day before the evacuation. About 10 per cent of the population managed to complete the census anyway. The agency went back in August primarily with the long-form census, and over all, with the use of administrative data as well, believes it got about a 90-per-cent response rate. Its final tally was 66,573, a rate of growth of 9.9 per cent from 2011.

"Everything we have indicates we have a very strong population count for Fort McMurray," Mr. Hamel said.

If communities disagree with the census findings, there is a process whereby they can ask for a review. After the 2011 census, for example, the province of Manitoba argued that the census had undercounted its population by nearly 20,000 people, a result that it believed had cost it nearly half a billion dollars in transfer payments. The result was reviewed but ultimately Statscan found no errors in its result.

Story continues below advertisement

There are 14 indigenous communities that Statscan has identified as being "incompletely enumerated." That number is much lower than in 2011, when it was 31, a figure that was higher in part due to forest fires in Northern Ontario. There are also six reserves that have returned results that Statscan suspects are undercounts and it expects to review that data.

This year's census was highly anticipated as it marked the return of the mandatory long-form questionnaire, which was axed in favour of a voluntary household survey in 2011. Many social scientists and business leaders had argued for the return of the long form because it's considered much more statistically reliable.

Statscan twice had to shut down its servers last May, in part to protect the data of the large number of people trying to file their census results, Mr. Hamel said.

More than 98 per cent of Canadians completed the long-form survey this year, compared with a response rate of 68 per cent for the voluntary National Household Survey. It was sent to a sample population of one in four households. Results from the long form were not part of Wednesday's data release but six further release dates are planned for later in 2017.