Massachusetts Institute of Technology Department of Urban Studies and Planning 11 520 A Workshop on Geographic Information Systems 11 188 Urban Planning and Social Science Laboratory Making Sense of the Census Introduction to the U S Census of Population and Housing Overview What is it and why do we care How the data are collected What data are available Introduction to Census geography and summary levels A Quick Look at the Census documentation A Quick Look at some sample data What is it and Why Do We Care Mandated by the Constitution of the United States The modern census of population and housing was established in 1940 with the incorporation of the housing component and the introduction of sampling techniques for the long form Conducted every ten years Attempts an actual count of population categorized by various criteria The only source for demographic data with a wide geographic scope The most reliable and detailed information for describing local area neighborhoods cities counties The most consistent source of time series demographic data available Federal dollars for schools employment services highway assistance housing construction hospital services programs for the elderly etc are all distributed based on census figures Also congressional representatives are apportioned based on census counts How the Data Are Collected Collected from households through a mail survey conducted every decade For the 2000 Census more than 285 000 census takers and support personnel have worked to account for the 118 million households and 275 million persons in the United States 2000 Census Two different census questionnaires are distributed o short form questionnaire contains questions asked of everyone o long form questionnaire contains questions asked of a population sample 1 6 households What s Included Information on Population Employment and Housing Characteristics Short Form 100 sample STF1 o Population Characteristics Housing Characteristics Age Tenure Gender Value or Contract Rent Race Vacancy Status Hispanic Origin Number of Rooms Marital Status Units in Structure Household Type Congregate Housing Household Relationship o Sample Short Form from 2000 Census Long Form STF3 o Population Social Characteristics Education Citizenship Ancestry Language Disability Children Place of Birth etc o Economic Characteristics Income Labor Force Status Employment Place of Work Public Assistance Retirement Income etc o Housing Age of Housing Heating Fuel Facilities Vehicles Mortgage Status etc o Sample Long Form from 2000 Census Why We Need to Know the Two Components o Accuracy of the data varies and counts differ Why o It helps us to understand how the data are organized in Summary Tape Files STFs Census Geography and Summary Levels The Census organizes and aggregates data into a series of geographic hierarchies Overview Summary Geographic Unit Level 010 020 030 United States Region Northeast NE Midwest MW South S and West W Regions Division NE New England Mid Atlantic MW East North Central West North Central S South Atlantic East South Central West South Central W Mountain Pacific 040 State includes Washington D C 050 County 060 County Subdivision 070 080 Place Census Tract Block Numbering Area average 4 000 persons 090 Block Group average 1 000 persons 100 Block average 85 persons State County Tract Block Group Nesting Summary Level 040 050 140 150 Geographic Unit State includes Washington D C County Census Tract Block Group Supplemental geographic areas Summary Level Geographic Unit 400 Urbanized Areas 300 Metropolitan Areas MSAs CMSAs 200 American Indian and Alaska Native areas 800 ZIP codes A Sample of SUMMARY LEVEL information from the STF3 Documentation A Visual Look at Census Geography o Continental United States Regions blue Divisions green States brown o Counties o A Closer Look at Southern New England Counties o Tracts in Suffolk County MA o Block Groups in Suffolk County Massachusetts black lines tracts in green Census Geography Concepts o The census block is the basic level o Confidentiality must be maintained and data about individual persons and households are not revealed o More detailed data are provided for higher levels of geography Why o Many but not all items are available at multiple summary levels Potential Problems o The same geographic name is used for summary levels corresponding to different aggregations o Geographic areas at lower levels may be subdivided by higher levels of geographic units e g split census tract o The same variable names are used for different variables in the STF1 and STF 3 o Variable value encoding makes identifying the meaning of variable difficult o ZIP codes do not overlay other units cleanly o Geographic boundaries change with time making time series analysis difficult Summary Tape Files Available on CD ROM and Possibly Online STF 1 100 count data from the short form o A States and subdivisions to the block group level o B Block level o C Entire U S and major subdivisions o D Congressional Districts STF 3 Sample data from the long form o A States and subdivisions to the block group level o B 5 digit ZIP codes o C Entire U S and major subdivisions o D Congressional Districts A Quick Look at the Census Documentation STF 3A Documentation Table of Contents STF 3A Variable Locator Subject Locator Table Definitions Matrix Using the File List of Census Tables by DBF File State County FIPS Codes Summary Level Sequence Charts STF3A CD ROM for Massachusetts and New Hampshire revised 1990 Census Lookup a forms driven Census information access system Online Census CD ROMs at the University of California List of CD ROMs available via NFS Warning Access to these online CD ROMs is slow While it is possible to use these files on the MIT server you will need to use a special form of the attach command attach n e View the attach online manual page via man attach A useful web site for getting a quick look at 1990 Census data is the Census Lookup Site at http venus census gov cdrom lookup More Information About the 2000 Census Response Rates for 2000 Census Data Release Dates Subjects Areas of Questions Asked The section of these notes entitled Introduction to the U S Census of Population and Housing is adapted from a Microsoft PowerPoint presentation created by Qing Shen for a lecture he delivered to the MIT class 11 208