The Constitution of the United States, ratified in 1788, calls for a decennial (every ten years) census of the population. The first Federal Census was taken in 1790.
At first, the census was intended only as a basic population count and merely asked: How many people lived in the United States? The answer to this question was used to decide how many Representatives each state could send to Congress. Only white "heads of household" - usually male, although in the absence of a man a woman was considered the "head" - were named; all other people, including children and enslaved Africans, were only counted, not named. Native Americans were not counted at all.
Over the course of the 19th and 20th centuries, more and more information was recorded during each census. The count expanded to include more people - "Indians" were counted starting with the second census in 1800, and African Americans were included as free people in their own right for the first time in 1870. Facts such as each individual's name, age, place of birth, and occupation were also added to the census form over the years. Today the census is a comprehensive research tool used to learn about migration patterns, population change, literacy rates, income, and other vital statistics that help scholars and lawmakers plan for the future.
For many people in 19th and 20th century America, the census was the only official record that paid them any attention. If a person did not own property, engage in scandalous behavior, or otherwise interact with courts, schools and newspapers, that person could end up invisible to modern historians. We often think of history as being populated by well known characters like George Washington or Harriet Beecher Stowe. That is because the papers and correspondence of prominent people - inventors, politicians, military heroes, authors and artists - are more likely to be collected, preserved and studied than those of the everyday man or woman. But what about the men and women who lived their everyday lives without fame and fortune? Some "ordinary" people are remembered today thanks to diaries, letters, photographs or oral histories, but not everyone left a written or visual record. Archaeology can also help us tell an "ordinary" person's story, but more often than not later development and building has destroyed any remnants of a site. The census, however, doesn't care if you're famous or rich - the census records everyone. People who would otherwise fall through the cracks of history can be found in the census, if you know where to look.
So what can the census tell us about these "ordinary" people? By the late 19th century, census records had become standardized documents, indicating where individuals lived, and who they lived with; their place of birth, and that of their parents; occupation; age; "race"; and language spoken. Often people can be followed through the years, allowing historians to watch families grow, jobs change, and populations move.
Unfortunately, the census does have its limitations. Census takers are only human; spelling errors, miscommunications, accidental number changes, and the like abound in the hand-written records. And now as modern transcribers attempt to read and type up the old documents additional mistakes have the potential to enter the record. All of this might add up to Lula Ambush, age 23 in the 1900 census suddenly becoming in the 1910 census Leila Bush, age 31. For the historian, Lula Ambush would, by all appearances, have disappeared from the record and Leila Bush would seem a different individual all together.
Cultural and language differences between an individual and the census taker also caused problems. This is especially problematic for our research into the Chinese immigrants in Montgomery County. It is unclear whether the Chinese names are written down in the Western fashion (family name second) or in the original manner (family name first). In addition, the vital statistics provided by the census only take the story so far. In the case of Mr. Lee of Rockville, he is described as "married," and his coworker Wong You is noted as Lee's "cousin." Where is Lee's wife? Unfortunately, the census had no category to record this information. Was Wong You really Lee's cousin, or was that the easiest way for Lee to describe his coworker? Or perhaps the census taker simply decided that the two Chinese men, the only ones in the city, must be related. We don't know the answers to these questions. Nonetheless, the census records in their limited way provide the most intimate look at Mr. Lee and his countrymen, because little else survives of their time in Rockville.
Using the Census
Census records are available for research in many places.
The federal census website provides basic reports for most years - http://www.census.gov/history/www/through_the_decades/overview/
The census website also offers hints for using the records for genealogical research -http://www.census.gov/history/www/census_then_now/genealogy_tips.html
The raw census data can be searched on several genealogical websites, although many of these sites require paid membership to access the data. The Montgomery County Historical Society's Jane C. Sween Research Library can provide access to some of these websites. The library also has the Montgomery County census data available for much of the 19th century.
It is worth noting that the majority of the 1890 census was destroyed by fire in the 1920s, so most of that year's data is lost. 20th century census data is released to the general public 72 years after it was originally recorded; as of now 1930 is the most recent year for which the full report is searchable, the 1940 records will presumably be released in 2012.