Although the U.S. was the first country in the world to call for a regularly-scheduled census, (the first U.S. census was in 1790) it was not the first to call for a census. The first official recorded census was called for by William the Conqueror shortly after his successful invasion of Britain in 1066. His main purpose was to keep track of all the people in his new domain, including all the property they owned. The property of any person considered an "enemy of the state" was confiscated and distributed as gifts among William's entourage. At the very least, those records were used to determine just how much tax or "contributions" each person would provide to the state. This list, which constitutes a book, became known as the Doomsday Book.
As noted above, the first U.S. census was held in 1790 and a new census is conducted every 10 years. Under current law, each census becomes full public record after 70 years. So in the year 2000, the 1930 census became available for research.
These records are normally bound as one book for each state, and the information in them can be reviewed at most genealogical and historical libraries, often on microfilm or microfiche.
There is a "Heads of Families" index to the 1790 census, and it includes Virginia. These records were extracted from Virginia Counties Tax Lists for 1785 through 1787.
Most local genealogical and historical societies and libraries have copies of census records for their area. Also, state groups usually maintain copies. Of course, the National Archives and Records Administration (NARA) maintains most of the originals and has microfilm copies available. You can access these microfilms through the Regional Repositories for Federal Archives located throughout the country. Some internet sites also offer access to U.S. Census records, for a fee; although free access may be available through your local library or Family History Center.
Family History Centers, (genealogy libraries operated by the Church of Jesus Christ of Latter Day Saints) either have, or have access to, all available U.S. Federal and state census records. You do not have to be a member of that church in order to use the centers. Because there are more Family History Centers than there are Federal repositories, you may find it much more convenient and less expensive to use their resources.
The easiest way to begin your search of a particular census is through the census index. The index normally includes every surname found in that index, followed by the county and/or township a person was living in at the time the census was taken. Using the information from the index, you'll know the particular section of the census you need to search for family information. You'll have a key to more places to search for family records and land records. Use the information on a census to help verify data you may already have, but remember, census takers made mistakes, too. The most obvious are spelling errors. Try every conceivable spelling of the surname, especially phonetic.
Once you've found the family you are looking for on actual census image, don't stop there. A major oversight by most beginners is to fail to check the pages before and after the one your ancestor is named on. Often you will find other family members living nearby. Always keep track of everyone in your family's household. That "farm laborer" may turn out to be Cousin Tillie's "future" husband. Also note the surnames of neighbors. Families and friends often migrated together and those friends may show up in your collateral lines.
If you are searching your Native American ancestry, there are some caveats regarding census records. Prior to the reservation period, Indians that lived away from the tribe were often enumerated. Usually the category assigned to race would read "Freeman" on older census sheets and then later, "colored" or "mulatto." There was no category for "Indian." Many researchers who see the term Freeman or colored often, incorrectly, assume their ancestor was black. This is a major problem with more recent Virginia census rolls (1900 to 1930), as even people claiming Indian ancestry were recorded as black on the census. If you can trace your family back to early Colonial times and find various references as either mulatto, or later as white, chances are your ancestor was Indian.
After the forced removals of Indians, many people elected to hide their Indian ancestry or face the loss of all the property they owned. You may find a census on that person where the category of race is marked "w" for white. After the removals, Indians on reservations were not enumerated in the U.S. Federal Census. They are recorded on individual tribal rolls and other types of census data.