Prepared by Elisabeth Lindsay.
The census survey is a study of census records for a single individual or family over time. Census records are highly useful tools for pinpointing ancestors in time and place; in addition, census records contain other important information such the approximate age of every person, where they were born, their relationship to the head of household, and may show extended family members living in the home or in close proximity. Following a person throughout his or her lifetime, using the census provides the "big picture" of a person's life and helps the researcher know where to look for additional records.
In the U.S., the census was taken every ten years since 1790. The census between 1790 and 1840 included names only for the head of household, but in 1850 the census enumerated by name every person in the household. Needless to say, the census since 1850 has proven the most useful to genealogical research. In days past, conducting a census survey meant searching each census individually and then moving on to the next. Today, census indexes are available online in which you can search all census years at one time, and can view images of the original census record. Of course, names were subject to change as people married, and names may have been variously spelled from one census to the next, but the process of researching the census and controlling for variation is much easier today than in the past. The census survey is a primary tool in genealogy and comes back into play time and again throughout the research process.