Data tabulation issues are focused on those processes where the data collection ends. Data tabulations encompass all aspects of the Census Bureau involved with processing the basic record database. It also includes provisions made through the Census Bureau for the [prospective] external Census Bureau data user to tabulate data from the basic record database (a potentially new feature for Census 2000, not available previously). Products are those sets of tabulated data organized by the Census Bureau for public access and encompass the preplanned conventional printed reports, data files and Internet based cyber-products. Products also include important "by-products" from the decennial census such as the TIGER/Line files.
A variety of maps, boundary files, and other geographic resources are available to help users locate and identify geographic areas. These resources are available in various media such as the Internet, CD-ROM, DVD, and, in the case of maps, as print-on-demand products.
Census 2000 ZIP/ZCTA-County-MSA Equivalency File
The Census 2000 ZIP/ZCTA-County-MSA (ZCM) Equivalency File is now available for downloading. The ZCM equivalency file enables a user to associate a ZIP/ZCTA code with the county(s) and metropolitan area(s) in which it is located. Additional information is available at http://proximityone.com/zctadata.htm.
Census 2000 Geographic Identification Code Scheme
The Census 2000 Geographic Identification Code Scheme (GICS) is now available for downloading. The GICS provides an integrated listing of counties, MCD/CCDs, places/CDPs, and remainder of MCD/CCD for each of these types geographic areas for the state. For each of these areas, the GICS provides the summary level code, FIPS code for each type of geography, name of the area, and the Census 2000 population and housing counts. Additional information is available at http://proximityone.com/gics.htm.
Census 2000 Map Files
Map files developed by Proximity, based the Census 2000 TIGER/Line files, and are now available for all states. There is no license for these data. The files may be used in any manner.
The files are organized on a state-by-county basis. Boundary files are available for all counties, school districts (all types), census tracts, block groups, and census blocks. A street/road feature file is available that contains all streets/roads in the TIGER files enabling a street feature overlay to be superimposed on any of the geographic polygon themes using alternative mapping software.
The primary map file download page is at this URL: http://www.proximityone.com/maps2000.htm. It is recommended that you register to receive e-mail updates about the Census 2000 Data Access and Use Web site (this Web site) so that you can keep up-to-date with related new developments.
1990 Census-to-Census 2000 Tract Relationship Files
10/22/2001: The Census Bureau has released the 1990 Census-to-Census 2000 Tract Relationship Files on the Internet. A description of these county-based files and how to access them is available at:
These files enable comparison of 1990 Census with Census 2000 census tract geographic areas. Total population data are provided in the files as well as geographic relationships.
1990 Census-to-Census 2000 Block Relationship Files
The 1990 Census-to-Census 2000 Block Relationship Files are used to determine Census 2000 geographic area equivalences for service areas, corridors, environmental impact areas, and other types of 1990 Census-based custom defined areas. Similarly, it is possible to determine the geographic area equivalence for Census 2000 Census Designated Places (greatly expanded for Census 2000) in terms of 1990 Census geography. This correspondence then enables the tabulation of 1990 Census demographics for the same area of interest as defined in Census 2000 and enabling improved longitudinal analysis.
ZIP Code Tabulation Area Boundary Files
Census 2000 ZIP Code Tabulation Area (ZCTA) boundary files in shapefile format are available for downloading. The files may be accessed via the http://www.proximityone.com/maps2000.htm that is further described here.
ZCTAs are new to the decennial census with Census 2000. ZIP Code Tabulation Areas are not the same as U.S. Postal Service ZIP Code Areas. See the summary description of ZCTAs.
The potential importance of the ZCTA map files and corresponding Census 2000 demographic data is very significant. Since many organizations have data about their customers or service locations by 5-digit ZIP code, it is relatively easy to develop summary statistics about customers/service locations aggregated to 5-digit ZIP code areas. However, demographic attributes about the total population in these areas is generally elusive. The availability of ZCTA demographic data may be a useful resource in meeting this need. The ZCTA boundary files, used in comparison with ZIP code boundary files, enable analysts to determine concordance between these polygons (ZIP versus ZCTA) in study areas of interest.
In developing the ZCTAs, Census started fresh to build areas to reflect the address ZIP Codes and locations that the Census Bureau had collected during the Census. Census has not compared ZCTAs to any commercially available ZIP Code boundary file. During the delineation process, Census did note use any ZIP Code boundary file or map as a reference source unless it came from the U.S. Postal Service. Instead of relying heavily on maps, Census focused on examining how well an assigned ZCTA code matched the address ZIP Codes in each tabulation block.
ZCTAs must conform to census tabulation blocks (which can often group together addresses with several different ZIP Codes). The blocks can cover large irregular areas, so a single block can significantly impact the size and shape of a ZCTA. There are also numerous blocks that exist on the margin of delivery routes and have no addresses. The assignment of ZIP Codes in these areas is anything but certain. Census has attempted to provide a reasonable coverage extension of ZCTAs into these unknown areas but other approaches might be just as valid. As a result, the biggest differences occur in more rural areas.
Demographic data for ZCTAs are available in Summary File 1 that is further described here.
TIGER/Line files [goto top]
2002 Version TIGER/Line Files. 2002 Version TIGER/Line files were completed in January 2003. This version of the TIGER/Line files contains references to "current" geographic areas which may differ from geographic codes, names and related attributes found in the Census 2000 version. There is little improvement in the scope of address-related data. To access/download these files, connect with the URL http://www.census.gov/geo/www/tiger/tiger2002/tgr2002.html.
Census 2000 Urbanized Area (UA) TIGER/Line Files. The Census 2000 UA TIGER/Line files were released on 5/3/02. These files may be downloaded via the URL http://www.census.gov/geo/www/tiger/tigerua/ua_tgr2k.html
The primary difference in between the Census 2000 UA version from the Census 2000 version is the inclusion of the Census 2000 Urbanized Areas (UAs), Urban Clusters (UCs), and Public Use Microdata Areas (PUMAs). Record structures are be slightly modified. For record structure information see http://www.census.gov/geo/www/tiger/tiger2k/ua_struc.html.
Assigning Urban Area Codes to census blocks. Consider the application where you have a county by census block shapefile(s) and want to be able to depict the Urban Area Code (UAC) in which each census block is located in a map display. One way to achieve this objective is to add the UAC to the county by census block shapefile dbase file. Then, a query can be performed to identify those census blocks which are in a particular UAC.
Though there are many ways to develop such a file, here is one method. The UAC and geocode hierarchy to get to the block level are contained in the composite of Census 2000 UA TIGER/Line files 1, A, and I. The appropriate TIGER/Line files can be downloaded from the Census server and processed with the Proximity TGR2DBF software creating a dbase structured version for these three TLFs. Next use TGR2DBF to create a census block-to-UA/UC code equivalency file (BLKUA.DBF). Next acquire the county by census block shapefile(s) from the Proximity map files website. Use the Proximity Cen2Shp software to merge the UA/UC code from the BLKUA.DBF into the county by block shapefile dbf. The augmented shapefile is now ready to support a display (or data link) of census blocks by user selected UA/UC. View the results of this process for the Lawrence, Kansas metropolitan area at http://proximityone.com/urbrural.htm.
If the objective is to obtain a UA boundary file, the county by census block shapefile could be "dissolved" on the UA code to create the UA boundary.
TIGER/Line Files -- Role and Scope
The Topologically Integrated Geographic Encoding and Referencing (TIGER) Line files contain geographic attributes for all earth surface line segments covered by the TIGER System. In the TIGER Line files, geographic attributes are coded for each side of a line segment and include geographic codes, street names, address ranges, and coordinates for use with geographic information systems for mapping and other applications.
An overview description of the Census 2000 version of the TIGER/Line files is available in the text document tgr2k.txt prepared by the Census Bureau.
Role and Importance of the TIGER/Line Files. The TIGER/Line files contain the underlying cartographic data, the source material, used in most Internet-based map server applications that have now become commonplace. Businesses and other organizations transform the raw material in the TIGER/Line files into content and formats needed to meet their own mapping and information locator needs.
The TIGER/Line files are derivative files, by-products, of the internal Census Bureau TIGER system that is used to facilitate collection and tabulation of data. The TIGER data also serves the needs of the Census Bureau to produce maps and perform related analyses associated with the mission of the Bureau.
The TIGER/Line files are also the dominant source of "boundary files" and related "theme and coverage" files used by mapping programs and in Geographic Information System (GIS) applications.
Increasingly TIGER/Line files are used in applications that merge imagery and satellite-sourced more real-time data.
The TIGER/Line files are widely used in "address lookup" applications. These applications often involve the need to locate a geographic code, such as a census tract code, based on an address. If addresses can be assigned geographic codes then corresponding address-oriented data may be aggregated to that type of geographic for analysis of the resulting summary data.
Census Bureau Census 2000 map resources are summarized below and at http://www.census.gov/geo/www/maps/CP_MapProducts.htm.
Urban Area Maps. Urbanized Area Outline Maps are available on the Census maps web site in PDF format. After the UA Outline Maps are completed, similar maps will be made available for Urban Clusters (UCs). These maps represent the areas as originally designated in the May 1, 2002 Federal Register Notice (the corrections from the August 23, 2002 Notice are not included).
Census block maps. The Census Bureau initially made copies of the PL 94-171 Census 2000 County by Census Block maps on the Web in Adobe Acrobat PDF format. The web page with the information about how to access and use these individual map sheet PDFs is located at: http://www.census.gov/geo/www/tiger/rd_2ktiger/pl_maps/pl_maps.html.
These maps show the boundaries, names, and codes for American Indian/Alaska Native areas, and Hawaiian home lands, states, counties, county subdivisions, places, census tracts, and census blocks. This map series will also be produced by specified governmental units (e.g., American Indian and Alaska Native areas, and Hawaiian home lands, counties, incorporated places, and functioning minor civil divisions).
Census tract outline maps. These county maps show the boundaries and numbers of census tracts and names of features underlying the boundaries. They also show the boundaries, names, and codes for American Indian and Alaska Native areas, counties, county subdivisions, and places.
Reference maps. This series of tabulation reference map types shows the boundaries for tabulations areas including: states, counties, American Indian reservations, county subdivisions (MCDs/CCDs) incorporated places, and Census Designated Places. This series includes the state and county subdivision outline maps, urbanized area maps, and metropolitan area maps. These maps vary in size from wall to page size.
Generalized boundary files. These files are derived from processing the TIGER/Line files. They are used with geographic information system (GIS) or similar computer mapping software. Boundary files are available for most levels of census geography.
Statistical maps. Census 2000 data will be displayed on colorful maps on such topics as population density and population distribution.