Census Geography Lacey Loftin U.S. Census Bureau Geospatial Foundation at Census Topologically Integrated
Geographic Encoding Referencing TIGER Classes of Census Geography Political Geography:
States, Counties, Cities, American Indian Reservations, Minor Civil Divisions, etc These boundaries may change between censuses Statistical Geography: Census Tracts, Census Blocks, Voter Districts, Traffic Analysis Zones, etc Designed to display Census data for research and analysis in
the public and private sector and most do not change between censuses Geographic Hierarchy County Census Tract
Relatively homogeneous population characteristics Population ~ 1200-8000 Block Group
Lowest level for ACS data Block Bounded on all sides by
visible and nonvisible features A city block in urban areas State County
Tract Tract Block Group Block
Block History of the Census Tract 1790 First census 1890
First delineation of small geographic areas called sanitary districts 1906 Dr. Walter Laidlaw suggested the delineation of permanent, small geographic areas that would retain their boundary census to census
1910 Dr. Laidlaw divided NYC into districts and asked Census to do the same for seven other cities 1920 Dr. Laidlaw published data by district for NYC
1930 Howard Wipple became chairman of the Committee on Census Enumeration Areas and promoted the use of census tracts 13
History of the Census Tract 1940 The census tract became an official geographic entity for which the Census Bureau would publish data. Census tracts covered major cities and block number areas (BNAs) covered many other cities 1980
The number of BNAs increased and the criteria of the BNA matched the census tract 1990 Census tracts or BNAs covered the entire nation (and so do blocks)
2000 The BNA concept was retired and census tracts were defined nationwide. 2010 100th anniversary of the census tract!!
14 Where can you get TIGER data? https://www.census.gov/geo/maps-data/data/tiger.html Sources of Census Geography TIGER/Line Shapefiles
http://www.census.gov/geo/www/tiger/ Download files by county Get all levels of geography available for a county or state TIGERweb
http://tigerweb.geo.census.gov/tigerwebmain/TIGERweb_main.html Interactive and WMS access to roads, streams and various boundaries that are found in TIGER data. Shapefiles with Demographic Data
Select Geographic areas with SF1 data pre-joined Shapefiles or Geodatabases What About Updates? How does the Census Bureau keep the
geography current? Some Geographic Participant Programs Boundary and Annexation Survey (BAS) Updates all legal boundaries and names Boundaries used to tabulate data in: American Community Survey, Decennial Census,
Population Estimates Program Redistricting Data Program Public Law 94-171 Participant Statistical Areas Program(PSAP) Public Law 94-171
Enacted in 1975, directs the U.S. Census Bureau to provide redistricting data needed by the 50 states. Specifies that within a year following Census Day (by April 1), the Census Bureau must send the governor and legislature in each state the data they need to redraw districts for the United States Congress and state legislature.
Statistical Areas Program Involves local governments Conducted once each decade Includes; Tracts Block Groups Census Designated Places (CDP)
Summary TIGER holds all Census Geography The public can access the data through TIGER/ Line or via TIGERWeb Each piece of geography has a unique identifier that is needed to link it to the demographic data
Questions? Jim Castagneri [email protected]
