Prepared by Elisabeth Lindsay.
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.