Prepared by Elisabeth Lindsay.
A census is a country's periodic count of the population. In the United States, a census was called for by the Constitution to determine how many members of Congress could be allocated to each state. Over time, the census has evolved to include more demographic, economic, and social data. Until recent times, people hired as census takers went from door to door to collect information. Today, census forms are sent through the mail. Historically, some people, suspicious of government have sought to evade census takers or have been less than honest in providing information. Other factors that come into play include simple human error, the legibility of a census taker's handwriting, the misspelling or variant spelling of names, and intentional misrepresentation. To protect privacy, census records are not made public for a period of years; in the U. S. that time period is 72 years from the date the census was taken. In some countries an argument is being made as to whether census data should ever be made public.
Regardless of error, the census remains one of the most important tools in genealogical research, serving to locate and identify family members and trace a family's movements over decades. Access to census records has improved over time. Until quite recently, census records were available only on microfilm through certain libraries, and the process could be quite tedious, utilizing printed indexes or interpreting the Soundex to locate a specific film number. Today, online census indexes not only make it easier and more readily available, but also provide search capabilities that make locating those elusive ancestors a greater possibility than ever before.