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The Twenty-First Census: Census Day was April 1, 1990.

The Census Bureau relied on extensive user consultation prior to the census to guide its efforts to refine both the long and short form questionnaires and the resulting data products. The agency held close to 100 meetings with groups including interested citizens, state agencies and legislatures, and public and private organizations throughout the country. It also solicited recommendations from federal agencies.

Enumeration

The 1990 census used two questionnaires: A short form asked 13 questions to 100 percent of the population and a long form asked 45 questions to 20 percent. Questions on the long form covered topics as diverse as marital history, carpooling arrangements, number of stories in their dwelling place, presence of elevators, and type of cooking and water-heating fuel used. Questions about the presence of air conditioning, the number of bathrooms, and type of heating equipment were dropped from the housing section of the 1990 census.

An additional question on congregate housing (such as, “Does the monthly rent include any meals?”) was added and the question on disability was revised, replacing the 1980 question on ability to use public transportation with one on ability to go outside of the home alone and to take care of personal needs.

Efforts to Improve Coverage and Completeness

Americans were alerted to the importance of responding to the 1990 census by extensive public television, radio, and print advertising. Promotion activities included local “complete count” committees, information kits and lesson plans for schools (Census in Schools), for churches, local government outreach and partnerships, and pro bono public service announcements, costing approximately $67 million.

The Census Bureau built upon its “T-Night” and “M-Night” itinerate person enumeration programs from 1980 with “S-Night” (“S” standing for Streets/Shelters). S-Night was a one-night sweep, conducted in major cities, of homeless shelters nationwide and other areas where the homeless were known to congregate. Many in the media billed this event, which took place on March 20, 1990, as a “homeless census,” although there is no way to determine the proportion of the homeless population that was counted on “S-Night.”

Following the 1980 census, the Census Bureau initiated plans to study the possibility of statistically adjusting the 1990 census to correct for the undercount. As a part of a planned post enumeration survey (PES) the Census Bureau would complete a contemporaneous survey of households and compare the results to information from the census for the same block clusters. With these data, the Census Bureau hoped to be able to develop adjustment factors to compensate for the anticipated undercount.

In October 1987, the undersecretary of commerce for economic affairs announced that, because the Commerce Department did not intend to statistically adjust the census for either undercounts or overcounts, he was canceling the Census Bureau’s adjustment-related planning activities for the 1990 census.

In November 1988, New York City and a coalition of state and local interests joined forces to file a lawsuit to compel the Census Bureau to reconsider the use of statistical adjustment of the population totals in light of the expected undercount from the 1990 census. In July 1989, the Commerce Department and the New York plaintiffs reached a partial resolution of the lawsuit. The Census Bureau would reinstate the PES (but with a smaller sample size than originally planned) and use it to produce population data that had been adjusted for the projected undercount. These data would be judged against the unadjusted data by an expert panel – the Secretary of Commerce’s Special Advisory Panel (SAP), which would provide advice on whether to adjust the 1990 population figures.

Technological Advances

The Topologically Integrated Geographic Encoding and Referencing System (TIGER), developed by the U.S. Geological Survey and the Census Bureau, was introduced for the 1990 Census. It is a computerized representation of various map features such as streets, and rivers, and census geographic boundaries and their attributes such as latitude, longitude and address ranges. TIGER was used to geographically code addresses into appropriate census geographic areas, as well as to produce the many different maps required for data collection and tabulation.

In 1985 the Census Bureau was the first government agency to make information available on CD-ROM, a new and relatively untested medium. Six years later, detailed census data, which for several decades had been available only to organizations with large mainframe computers, was made accessible by anyone with a personal computer. As in 1980, 1990 census data were available in print, on computer tape, and on microfiche. In addition to these media and CD-ROM, selected data were also made available online through two vendors of online services- DIALOG and CompuServe.

Intercensal Activities

Demographic analysis showed that the 1990 census had an estimated net undercount of 1.8%, with an appreciably larger net undercount rate for African Americans than for other residents. The PES sampled 165,000 households in 7,500 blocks, and the Census Bureau compared this data with data from the census for the same block clusters. By comparing the data from these two sources, Census Bureau statisticians were able to estimate the numbers and characteristics of those missed or improperly counted by the enumeration. From there, the statisticians developed statistically adjusted population counts down to the block level.

In June 1991, the Undercount Steering Committee, a Census Bureau group charged with advising the director on adjustment recommended using the adjusted population counts. Following this recommendation, the director herself came out in favor of adjustment. However, the undersecretary of commerce for economic affairs, who oversees the Census Bureau disagreed. The secretary of commerce’s SAP split, four votes to four.

Responding to the mixed recommendations, the secretary of commerce announced in July 1991 that he did not find the evidence in favor of using adjusted counts convincing. He decided that the 1990 census would use the unadjusted totals.

Following announcement of the secretary’s decision, the New York plaintiffs resumed their lawsuit. The federal district court decided in favor of the Department of Commerce in April 1993. Plaintiffs appealed the ruling, and the U.S. Court of Appeals rejected the district court ruling and ordered that the case be returned to the district court for further proceedings. The issue was finally taken up by the Supreme Court, which in March 1996 upheld the secretary’s decision not to adjust the 1990 census counts, but did not rule on either the legality or constitutionality of the use of statistical adjustment in producing the apportionment counts.

Further Information

• A detailed procedural history of the 1990 census is available in Procedural History: 1990 Census of Population and Housing [63 MB]
• Reports and statistics from the 1990 census

Information provided from Census.gov

The Twentieth Census: Census Day was April 1, 1980.

Enumeration

Due to the success of the mail-out/mail-back questionnaire in 1970 the program was expanded for 1980 with about 95 percent of the U.S. population now enumerated in this manner.

The 1980 short form contained 7 population questions and 11 housing questions; the long form contained an additional 26 population and 10 housing inquiries. A question on Spanish or Hispanic origin or descent was added to the 100-percent questions for the first time; in 1970 this question was asked of only 5 percent of the population.

The 1980 census also included two small surveys. The Components of Inventory Change Survey obtained information on the number and characteristics of housing units that changed or stayed the same between 1973 and 1980. The Residential Finance Survey collected data on mortgages, shelter costs, selected housing characteristics and owner characteristics.

Efforts to Improve Coverage and Completeness

An extensive public service advertising campaign directed by the Census Bureau’s Census Publicity Office, which was established in 1978, focused on increasing the public’s awareness of the census and encouraging people to complete and mail back their questionnaires. The Census Bureau secured the free services of the Advertising Council, which in turn hired the firm of Ogilvy & Mather to develop the campaign.

Additionally, the Census Bureau made a special effort to enumerate historically undercounted groups during two programs, “M-Night” (“M” for mission) and “T-Night” (“T” for transient). On M-Night, specially trained enumerators counted people staying in homeless shelters, soup kitchens, bus and rail stations, dormitories, and others. On T-Night, the enumeration focused on hotels and motels with permanent residents.

Technological Advances

The Census Bureau developed the State Data Center Program to simplify public access to data available on computer tapes. Agreements between state governors and the director of the Census Bureau committed the agency to provide free copies of any Census Bureau electronic and printed information and products to the states; the states, in turn, agreed to develop a network of affiliate organizations (state executive departments, chambers of commerce, councils of governments, university research departments or libraries) by which census information would be delivered to local users. By the mid-1980’s all states were participating in the program, which encompassed about 1,200 state and local organizations.

Intercensal Activities

Demographic analysis of the 1980 census showed that once again the census, despite reaching the overwhelming majority of people in the United States, undercounted the population, this time by about 1.2 percent. More troubling, the estimated net undercount rate for African Americans was 3.7 percentage points higher than that for all other races combined.

Before the enumeration process had finished, the city of Detroit sued, demanding that statistical adjustment be used to compensate for those estimated by the Census Bureau to have been missed or improperly counted. Shortly thereafter, several other states and localities, including the city and state of New York, also filed suit. The Census Bureau announced in the fall of 1980 that it did not plan to adjust its population totals using statistical methods because it could not be sure of the number and distribution of illegal aliens and other undercounted groups.

The New York suit would eventually become the most prominent case; a federal district court ruled in the plaintiffs’ favor in late 1980, ordering the Census Bureau to adjust its numbers to correct for the undercount. The Supreme Court stayed this and other rulings in December 1980, allowing the Census Bureau to report its unadjusted figures to the president. A federal appeals court finally ruled, in 1987, that the census figures should not be adjusted to account for the undercount because the Census Bureau’s decision not to adjust was not arbitrary and capricious.

Further Information

• A detailed procedural history of the 1980 census is available in Procedural History: 1980 Census of Population and Housing [ZIP 80MB]
• Reports and statistics from the 1980 census.

Information provided from Census.gov

The Nineteenth Census: Census Day was April 1, 1970.

In 1966, the Census Bureau solicited suggestions from its advisory committees and from the general public about the makeup of the census and the availability of the resulting data products. It instituted a series of 23 local public meetings around the country to broaden the scope of its efforts, which resulted in numerous proposals for additional inquiries about the scope and structure of the census, and interest in increasing data products published, particularly for smaller areas such as blocks.

Enumeration

Studies after the 1950 and 1960 censuses revealed that those censuses had undercounted certain segments of the population. Researchers also noted a growing distrust of government and resistance to responding to the census, despite an increasing need for accurate information in both the private and public sectors. In large measure, the increased need for data resulted from the federal government’s reliance on population and other information collected by the census when distributing funds to state and local governments. In an effort to reduce the complexity of its products, the Census Bureau reduced the number of inquiries on the long-form questionnaire from 66 to 23.

The Census Bureau created an address register for densely settled areas that U.S. Post Office employees who were familiar with their routes were instructed to correct and update as needed. The register was also used to ensure that all housing units were accounted for when enumerators had completed their assignments.

The U.S. Post Office delivered census questionnaires with instruction sheets to every household several days prior to Census Day. In areas with a substantial number of Spanish-speaking households, a Spanish-language version of the instruction sheet was also enclosed. For the first time, a separate question on Hispanic origin or descent was asked, but only of a 5 percent sample of the population.

Also for the first time, residents of urban and surrounding areas were instructed to mail their forms back to the Census Bureau where enumerators reviewed them and used follow-up interviews to check on missing or incorrect responses. Rural householders received questionnaires in the mail, but were asked to hold the form for pickup by an enumerator. A letter explaining the need for the data collected and emphasizing the confidentiality of responses accompanied all census questionnaires.

Sampling

Only 5 questions were asked of all individuals: relationship to household head, sex, race, age, and marital status. Other questions were asked of a 15 percent sample and still others of a 5 percent sample. Questions common to both samples resulted in a 20 percent sample.

Technological Advancement

Computerized address lists, called Address Coding Guides, helped assign census geographic codes to questionnaires.

A major innovation for the 1970 Census was the production of a series of computer tape files, called “Counts.” Counts one, two, and three contained complete count data for block groups/enumeration districts, census tracts and minor civil/census county divisions, and blocks, respectively. The fourth through sixth Counts provided sample data for geographic areas of varying population size. The Census Bureau also produced six Public Use Microdata Sample files, each containing complete information for a small sample of the population; roughly two million individuals. A variety of public and private institutions participated in the Census Bureau’s Summary Tape Processing Center Program, a loose-knit group of organizations that processed data from the 1970 census computer tapes.

Further Information

• A detailed procedural history of the 1970 census are available in Procedural History: 1970 Census of Population and Housing [ZIP 165MB]
• A wide variety of historical statistics from this and other decades is available in Historical Statistics of the United States: Colonial Times to 1970. It is available as a PDF [74.4MB] or 2-part ZIP file: Part I [52.2MB] | Part II [66.1MB].
• Reports and statistics from the 1970 census.

Information provided from Census.gov

The Eighteenth Census: Census Day was April 1, 1960.

Enumeration

1960 marked the birth of the first mail-out census. Earlier censuses had used self-enumeration on a limited scale, but 1960 was the debut for this technique as a primary method for the collection of population and residential data. The postal service delivered questionnaires to every occupied housing unit. Householders were asked to complete the questionnaire and hold it for an enumerator to pick up.

Enumeration efforts were divided into two stages. The first stage concentrated on the quick collection of a few data items for every person and dwelling unit- information available from responses to questions on the questionnaire that had been delivered to every household. The second stage focused on the collection of more detailed economic and social information from a sample of households and dwelling units. Second stage questionnaires were hand-delivered by enumerators when they came to pick up the first form. Households receiving the second questionnaire were asked to complete the form and mail it to their local census office in postage-paid envelopes provided by enumerators.

In areas of low population density, the two-staged enumeration was combined to allow enumerators to collect and record sample data at the same time they came to fill out the general questionnaire.

Sampling

Additional sample questions were asked of 25 percent of the population. In urban areas (accounting for about 80 percent of the nation’s population), enumerators carried questionnaires containing the sample population and housing questions for every fourth housing unit. If the units were occupied, the householders were asked to complete the sample questionnaires and mail them to district offices. If the units were vacant, the enumerators completed the questionnaires.

The greater use of sampling meant that the totals for some less populated areas were subject to moderate amounts of sampling variation, which did not significantly impair the usefulness of the statistics gathered. Using a 25 percent sample of households eliminated nearly 75 percent of the processing expenses that would otherwise be required.

Additional questions, which had been discussed but not included in several past censuses, focusing on place of work and means of transportation to work were added in 1960.

Technological Advancement

Computers processed nearly all data from the 1960 census. For the first time, the Census Bureau used a film optical sensing device for input to computers (FOSDIC). This machine “read” and converted to code on magnetic tape data appearing on returned questionnaires thus eliminating the time and expense for the previously necessary step where clerks entered the data on punch cards. The questionnaires for 1960 were designed so that respondents could indicate their answers by marking small corresponding circles on the page. The completed questionnaires were photographed onto microfilm with automatic cameras; FOSDIC then read the blackened dots (which appeared as clear holes on the negative film) and transferred the data they represented to magnetic tape for the computer at a speed of 3,000 items per minute. Later versions of the FOSDIC device were able to process up to 70,000 items per minute.

Further Information

• A detailed procedural history of the 1960 census is available in 1960 Censuses of Population and Housing: Procedural History [66.7 MB]
• A wide variety of historical statistics from this and other decades is available in Historical Statistics of the United States: Colonial Times to 1970. It is available as a PDF [74.4MB] or 2-part ZIP file: Part I [52.2MB] | Part II [66.1MB].
• Reports and statistics from the 1960 census.

Information provided from Census.gov