Census records are amongst the primary tools of genealogists. Even so, those of us who have been reading them for a while can tell you that the records are not as reliable as we would wish. I am still trying to find great-great-granddad in the 1850 census although he appears hale and hearty in the enumerations of 1840, 1860, 1870 and 1880. His absence in 1850 is still unexplained. Still, my quandary is minor compared to some others. For instance, the 1990 census is thought to have missed one native American in eight. Thousands of others – perhaps millions – have been missed in census records taken over the past two centuries.
America's first census was carried out in 1790, and it was groundbreaking in many ways. It was the first to be mandated in any country's constitution. It also caused America's first presidential veto when George Washington, on the advice of Thomas Jefferson, disagreed with legislation defining how this “apportionment” was to be carried out. Washington’s primary objection to the proposed amendment was that “there is no one proportion or divisor which, applied to the respective numbers of the States, will yield the number and allotment of representatives proposed by the Bill.” It is interesting to note that today’s fixed allocation of 435 seats also does not pass the test established by President Washington.
An article from 2007 in The Economist compares the U.S. Census with similar efforts in other countries. “Where government is oppressive, people want to keep out of censuses, lest information they provide is misused. Where government provides, people want to be in censuses, and to boost their numbers, in order to claim a larger share of the goodies.”
The Nazis used population records to round up Jews into concentration camps. As a result, Germans are still reluctant to be counted. In 1936 Stalin told his officials that the following year's census would find a total population of 170 million—a figure that did not account for his slaughter of millions in famines and purges. The enumerators (census takers) found only 162 million people and revealed other unwelcome facts, including that nearly half the population of his supposedly atheist country was religious. With this news Stalin denounced the count as a “wrecker's census” and had the census takers either imprisoned or shot.
A new count in 1939, apparently conducted by a new team of enumerators, gave Stalin his figure of 170 million.
You can read more about census records at http://www.economist.com/displayStory.cfm?story_id=10311346.