Some of the first records beginning genealogists look for are those in the U.S. Federal Census. My first experience with the U.S. Federal Census was not entirely successful. I was doing research in the Family History Library in Salt Lake City, Utah, long before the census records were digitized and computerized with an index, and I looked for one of my ancestors and found the microfilm copies to be unreadable. It was probably about twenty years before I took another stab at searching the Census.
Today, of course, the experience is completely different. The U.S. Federal Census records are probably the most accessible and easiest to research of any of the records in the United States on a Federal level. There are copies of the Census or indexes of the records in multiple locations on the Web. I am not sure I can list all of the copies, there seems to be a new set of records added regularly. Most of the large commercial websites have a complete or partial copy and there are also copies for free. Here is what I know today about the copies online:
- FamilySearch.org Historical Record Collections -- FamilySearch has a complete index of all of the census years, but the images for the 1810 and 1860 are on other websites. FamilySearch also has many of supplemental schedules. Free
- Ancestry.com -- A complete, indexed set of the U.S. Federal Census records with many of the supplemental schedules. $
- Fold3.com -- Owned by Ancestry.com, Fold3.com has a partial set of census records. Only the 1860 U.S. Federal Census is complete. $
- Archive.org -- This free website has the complete images of all of the U.S. Federal Census records from 1790 to 1930, however there is no index. If an image is missing from another website, it is probably available on Archive.org. This site also has complete copies of all the supplemental census records, although, I must caution readers that the website is difficult to search and finding the census records is a challenge. You can get the complete list from this link https://archive.org/details/us_census. Free
- Archives.com -- Another Ancestry.com website has a complete set of U.S. Federal Census records from 1790 to 1940. $
- Mocavo.com -- Currently owned by Findmypast.com, this website also has a complete, searchable copy of the entire available U.S. Federal Census from 1890 to 1940. Free search
- 1940Census.archives.gov -- Official 1940 Census Website. Free
- CensusRecords.com -- Owned by Findmypast.com, this website has a complete, searchable set of U.S. Federal Census records. $
- Findmypast.com -- Complete, searchable set of U.S. Census records with some supplementary schedules. The 1940 U.S. Federal Census is free. $ and free
- HeritageQuestOnline.com -- Available only through libraries, this website has a complete, searchable set of the U.S. Federal Censuses. Free in participating libraries.
There are other partial transcriptions and selections. I also suggest checking Cyndi's List for United States, U.S. Census.