Census Data and Publications Eleanor Chase & Cass Hartnett University of Washington Libraries Government Publications

Definition of Census A complete enumeration of a population or the business and commercial establishments, factories, farms, or governments in an area.

Decennial census The census of population and housing Taken by the Census Bureau in each year ending in zero

Why take the U.S. census? Required by United States Constitution Article 1 Section 2 for the purpose of apportioning seats in the U. S. House of Representatives

Privacy concerns The Census Bureau is bound by law not to disclose information that would allow you to identify an individual So the data that is released at the block level is limited If you need the data from the long form questionnaire, the smallest geography is the block group (1960 – 2000)

How is it taken? First decennial census of population was taken in 1790 http://www.census.gov/prod/www/decennial.html The most recent census was in 2010

The census attempts to be a complete count of the population and reach every household and individual In 2010, 74% of the population returned their questionnaire via mail, see http://www.census.gov/2010census/data/ Many others were counted in person by census workers

Questionnaires For decades, there were two questionnaires 80% of the population received the short form http://www.census.gov/dmd/www/pdf/d61a.pdf The remaining 20% received the long form http://www.census.gov/dmd/www/pdf/d02p.pdf

Why are the questions asked Why are the questions asked? The questions asked on the census questionnaire provide data that are required by federal law to be collected. Each census has had a separate act of Congress to approve the questions on the questionnaire.

Data and geography considerations The larger the geographic area, the greater number and detail of tables published Especially for small areas, more data is available on electronic files than is printed (for the 1980-2000 years) The smaller the geographic area, the more likely it is that data will be suppressed (i.e. not published). Data for small areas are more subject to certain kinds of error than are data for large areas. Boundary changes from one census to another must be taken into account when making historical comparison.

Census Geography Nation The fifty states and the District of Columbia Each of the fifty states, District of Columbia, Puerto Rico, the Island Areas are treated as state equivalents County The primary legal division of a state, except for Alaska (boroughs) and Louisiana (parishes) Place i.e. city A concentration of population legally bounded by incorporation Census designated place (CDP) is the statistical counterpart of a place, but it is not an incorporated place.

The U.S. and its states

Washington state county outlines

Statistical geography Census Tract Small relatively permanent statistical subdivision of a county. Contains between 1,000 and 8,000 people, with optimum size of 4,000 people. Delineated with the intention of being stable over many decades, so the boundary generally follows relatively permanent visible features. County and State boundaries are always census tract boundaries

Statistical geography cont’d Block Group Subdivision of a census tract. All of the blocks that begin with the same number make the block group. This is the smallest level of geography for which detailed economic and social characteristics will be reported. Block The smallest geography in the census. Think city block bounded by four streets, but it could be another visible feature, railroad tracks, power line, a river, lake, etc.

Census tracts

Census tracts King County Washington

Portion of Census Tract 3 showing blocks and block groups

Metropolitan statistical areas Core based statistical areas consist of metropolitan and micropolitan areas The general concept of a metropolitan or micropolitan statistical area is that of a core area containing a substantial population nucleus, together with adjacent communities having a high degree of economic and social integration with that core. For 2000, each metropolitan area must have a nucleus of 50,000 or more Each micropolitan area must have a nucleus of 10,000 or more

Data considerations for metropolitan areas The area can cross state lines It is composed of entire counties except in New England, where cities and towns are used. The areas have changed over time Be cautious when comparing metropolitan data over time.

Washington state metro areas

Finding data Census 2000 was the first census to release the data first over the internet, with print publications following later www.census.gov Earlier censuses were released as printed volumes which the Census Bureau is putting on the internet http://www.census.gov/prod/www/decennial.html

www.census.gov

American FactFinder

UW Libraries Census Guide, Data Sources tab