Census of Population and Housing

Decennial Census Overview

The Decennial Census is an example of a modern periodic census, focusing on enumeration to determine the apportionment of political power.  Early censuses were for tax purposes and/or raising militia. It has been taken every ten years since 1790.  The latest was in 2020 with results and results will begin to appear in 2021. The next will be in 2030.

From its inception, the Decennial Census has been wrought with controversy.  Issues of quality control, timeliness, and continuity were raised time and time again.  Allegations of under counting and over counting, sloppy statistical analysis, etc., have plagued the census since day one.  Very little was done to address the problems cited until recently.

Timeliness was a major criticism.  By the time the data was compiled, analyzed and published, it was out of date.  Until 1890 the census was hand tabulated.  The 1880 Decennial took over 7 years to tabulate 25 questions.  Early on critics wanted to have a second census taken part way through the decade to give a clearer picture of the state of the nation.   In 1996 the American Community Survey was launched addressing this criticism of the census process.

Continuity issues have plagued the Decennial Censuses. It was overseen by four federal departments prior to 1900: first by the U.S. Federal Marshall reporting directly to the President (1790), then by the State Department (1800-1840), then the Department of the Interior (1850-1900), and finally the Department of Commerce where it has remained.  The issue of continuity was further compounded by the early practice of appointing a special bureau from scratch every ten years to handle the census and its tabulation and then disbanding it until the next census.  This practice led to very little continuity from one census to the next.  Since 1902 the census has been conducted by a permanent entity: the Census Bureau.  The Decennial census will always be dogged to some extent by continuity issues because from census to census the data collected has varied slightly reflecting the concerns and issues of the day.

The Decennial Census is actually two censuses taken concurrently every ten years, jointly called the Census of Population and Housing. The Census of Population, begun in 1790, counts the number of people and some personal, social, and economic characteristics, and is the oldest statistical product of the Federal government.  The second part of the Decennial Census is the Census of Housing.  Taken since 1940, it counts the number of residential dwellings and selected physical and financial characteristics.  Together they constitute the modern day Decennial Census.

Originally the census was set up to apportion the House of Representatives seats in Congress and is mandated by the U.S. Constitution.

Representatives … shall be apportioned among the several States which may be included within this Union, according to their respective Numbers, which shall be determined by adding to the whole Number of free Persons ... The actual Enumeration shall be made within three Years after the first Meeting of the Congress of the United States, and within every subsequent Term of ten Years, in such Manner as they shall by Law direct.... 

Early on business, civic leaders, etc., saw the potential value in the census and lobbied to have more questions dealing with other aspects of the American economy added to the census and not just those necessary to apportion seats in the House of Representatives. In modern times it has been also used to apportion federal funding, identify trends over time that can help predict future needs, etc.  Over the years the social and economic data collected has varied reflecting the changing political climate and concerns of the nation.

The first U.S. Census (1790) placed the population at 3.9 million and counted basically the population of the United States as mandated under the Constitution.  Although slaves were counted, Native American populations were not. By contrast the 2020 census placed the population roughly at 331.5 million and  theoretically counted everyone living in the United States and its five territories. The 1790 census was conducted by U.S. Federal Marshals going door to door, while the 2020 census was completed by respondents via mail, phone, on-online or as a last resort in person by a census taker. The 1790 census asked six questions:  name of head of family and number of persons in household and the number of persons in each household of the following descriptions:  Free White males 16 years and upward, free White males under 16 years, free White females, all other free persons (by sex and color). The 2020 census asked seven questions of everyone covering whether the dwelling was rented or owned, how many people lived in the dwelling, information on age, sex, race, ethnicity, and relation to the head of household.  A detailed list of the various questions asked on previous Decennial Censuses is available in  Measuring America: The Decennial Censuses from 1790 to 2000.

Through 1840, the Decennial Census remained basically a population count, and most of the changes that did occur involved refining details within various categories.  For example the 1790 Census collected data on white males under 16 years, and 16 years and older.  The 1800 Census collected data on white males and females under 10 years, 10-15 years, 16-25 years, 26-44 years, and over 45.  Although earlier censuses asked questions concerning industry, the 1850 Census is considered the beginning of the “modern census”.  

The 1940 through 1990 Decennial Censuses had two versions.  A short form asking basic questions about age, sex, race, etc. and a longer form administered to about one in six households that asked additional question on socioeconomic and housing issues.  Starting with the 2010 Census only the short form questionnaire will be used.  Detailed statistical information previously collected by the long form will be, in the future, gathered through the American Community Survey.  The Survey is based on a rolling or continuous measurement design model with any given address having a 1-in-480 chance being selected in any given month, providing a more accurate and timely statistical view of the changing demographics of the United States.

Although today the census is considered confidential, this was not always the case.  Prior to 1880 the census was considered a public record and was publicly posted for review and correction.  In 1879 Congress passed the Census Act of 1879 making census records confidential and in 1953 Congress passed legislation further codifying census record confidentiality (Title 13, U.S. Code).  With some notable exceptions during World War I and II, the Courts have upheld this despite numerous legal challenges.  The Census Bureau keeps an individual’s responses confidential for 72 years.  It cannot share this information with any other government agency.  After 72 years the census schedules and questionnaires containing an individual’s responses become available to the general public.   The 1950 census schedules are the most recent to become available, however not all of the earlier decennial schedules have survived.  Some have been destroyed by fire, the ravages of time, etc., leaving only the Census tabulations for historians and genealogists.  For more information, see the National Archives and Records Administration - Resources for Genealogists.

The Decennial Census has come a long way since the initial census of 1790.  Evolving as America has changed.  Initially a simple population tabulation taken on whatever forms the enumerators concocted into a sophisticated data tool that it is today.  It has evolved from a snapshot frozen in time to a continuously running video.  It tells who we were, who we are and where we going as a nation.


Further Reading

200 Years of U.S. Census Taking: Population and Housing Questions, 1790-1990.  Fredrick G. Bohme. Washington, D.C.:  United States Department of Commerce, Bureau of the Census, 1989.

Overview of the Decennial Censuses from 1790 thru 1990.

Encyclopedia of the U.S. Census:  From the Constitution to the American Community Survey.  Margo J. Anderson, Constance F. Citro, and Joseph J. Salvo, editors.  2ndEdition.   Los Angeles, California:  CQ Press, 2012.

Updated and expanded version of the 2006 edition. Highlights changes in the Census Bureau’s data collection and dissemination practices, as well as providing insights to the history, politics, content, procedures, etc. of the U.S. Decennial Census from the first in 1790 to the latest in 2010. It also discusses the American Community Survey released in 2010.

Measuring America: The Decennial Censuses From 1790 to 2000.  Washington, DC:  U.S. Department of Commerce. Bureau of the Census, April 2002.

An overview of the history of the U.S. Census of Population and Housing. Includes information on population schedules.

Modernizing the U.S. Census. Barry Edmonston and Charles Schultze, editors ; Panel on Census Requirements in the Year 2000 and Beyond, Committee on National Statistics, Commission on Behavioral and Social Sciences and Education, National Research Council.  Washington, D.C.  National Academy Press, 1995. 

Provides an overview of the census, discusses problems with the census such as cost, accuracy, data usage/misuse and offers suggestions for overhauling the process.

Twenty Censuses: Population and Housing Questions 1790-1980. Washington, D.C.:  U.S. Department of Commerce. Bureau of the Census, October 1979.

Details on how the population and housing inquires have evolved over the decades from 1790-1990.  Also available online.

Understanding the CensusMichael R. Lavin.  New York:  Epoch Books, 1996.

Detailed explanations of census terms, products, and uses.

U.S. Census Connections:  A Resource Guide:  Decennial Censuses of Population (Library of Congress)

Provides lists of resources for each of the decennial censuses including historical information, etc.

Using the 1990 Census for ResearchRichard E. Barrett.  Thousand Oaks, California:  Sage Publications 1994.

Provides an overview of the 1990 Census and issues and problems in using Census data.

The Who, What, and Where of America:  Understanding the Census Results.  Martha Farnsworth Riche and Deirdre A. Gaquin (editors).  Lanham, Maryland:  Bernan Press, 2003. 

Based on the 2000 Decennial long form results covers information on demographics, housing, transportation, migration, etc.