1940 - 2000
1940 - 1950 1940 was the first year that statistical sampling was introduced to the census, making it possible to ask a random subset of the population additional questions. Enumerators asked every 5th person 16 extra questions. Statisticians also realized that sampling could be used to check the results of the census. Sample surveying, a much more efficient and ultimately more accurate method than full-population census counts, represented a new level of technical sophistication at the Census Bureau.
When a census is taken, every individual is counted. The effort and resources required in this task are extraordinary. Many people are missed if they are not home, if they have no home or if choose to not answer the door. Because census enumerators are interviewing hundreds of millions of people, there are few resources left over afterwards to track down the people who do not respond. When a survey is taken, however, far fewer people are interviewed and it is much easier to devote the time and resources to contacting non-responders. Thus, if a census and a sample survey are coordinated, the more accurate sample survey can estimate the number of peopel missed by the more detailed census. The Census Bureau first applied this discovery to the 1950 census, where they found a 4.1% undercount.
1960 Continuing its efforts to streamline the census, the Census Bureau mailed its first questionnaires in 1960. This early mail-in questionnaires replaced the door-to-door enumerators in urban areas only, but represented a new direction in census efficiency and privacy.
1960 - 2000
Text is from Census History, retrieved 8.13.09.
From 1790 until 1960, the Census Office (and later Census Bureau) published all of its results and reports on paper. Even as computers began to take a larger role in processing census data in the mid-20th century, dissemination remained largely unchanged from the earliest census publications. Since 1960, the Census Bureau has been quick to take advantage of technological changes in data dissemination.
1960 - The Census Bureau produced its first magnetic tapes, containing results from the 1960 census. The data was recorded on a combination of "binary, binary-coded decimal, and XS3 tapes." These "test tapes" were produced well after the data became available in print.
1970 - All 1970 census data products were available on magnetic tape. Data from 1970 was contained on 2,054 reels of 7-channel, 556 CPI (characters per inch) computer tape. Six files, or counts, were produced.
1978 - State Data Center (SDC) program, a cooperative program between the states and the Census Bureau, was created. This program made data available locally to the public through a network of state agencies, universities, libraries, and regional and local governments. State governors had the authority to appoint SDC organization leaders.
1984 - Census data became available as CENDATA on the DIALOG and COMPSERV online databases. During the 1980's, the Census Bureau was a leader among government agencies in adopting several new technologies, especially online dissemination through private providers, and electronic bulletin boards.
1986 - Test Disc #1 issued, making the Census Bureau the first federal agency to produce a CD-ROM. Test Disc #1 contained data from 1980 Summary Tape File 3B, the 1982 Census of Agriculture, the 1982 Location of Manufacturing Plants survey, and 1982 County Business Patterns.
1988 - The Census Information Center (CIC) program started as a pilot project to make census data available to underserved communities, many of which were under-utilizing the information. The CIC program served to alleviate some of the access constraints that census planners believed accounted for much of the underutilization. The Census Bureau used community organizations to assist their CIC efforts. Also in 1988, the Business and Industry Data Center (BIDC) program, a complement to the SDC, was launched to fulfill requests from local business for economic data.
1990 - All 1990 census results were published on CD-ROMs.
1993-1994 - 1992 economic census was published on CD-ROM with 1987 historical data as a supplement.
1994 - The Census Bureau launches an Internet site, one of the first federal agencies to do so.
1996 - The Census Bureau makes the Internet the primary means of data dissemination. "The new dissemination plan will allow for quicker release of detailed data many people want."
1998 - The Census Bureau announces a major expansion of data dissemination on the Internet. American FactFinder is released with data from the 1997 economic census, 1990 population census, American Community Survey test and demonstration data, and results of the 2000 census dress rehearsal.
2000 - The Census Bureau uses Internet and DVD-ROM for dissemination of Census 2000 data.
2009-2011 - 2007 Economic Census data are published entirely via the Census Bureau's American Factfinder