About the 2000 Census Geodatabases on WAGDA
|This page contains narrative metadadata. Metadata has been created for each of the individual geodatabases in XML format according to Dublin Core standards, and can be viewed on the Download page. In addition, each of the geographic features have been assigned metadata based on FGDC standards by the State of Washington OFM, which can be viewed from within the ArcCatalog.
All data within the WAGDA geodatabases is within the public domain. When publishing maps or data from the geodatabase, the U.S. Census Bureau should be cited as the source.
|Census Data Source|
The Census SF1 (Standard File 1), also known as short-form data, is based on a 100% count of the entire population. It contains basic demographic information that includes total population, urban vs. rural population, race, gender, age, households, families, housing units, occupancy status, and tenure. Data from SF1 is available at all geographic levels down to census blocks (the smallest census unit).
The Census SF3 (Standard File 3), also known as long-form data, is based on a 1 in 6 sample of the entire population. In addition to the variables collected in SF1, it also contains data on ethnicity, place of work, employment, income, poverty, and a number of other variables. Data from SF3 is not available at the block level; the smallest available unit is the census block group.
In the 1990 Census these files are referred to as STF1 (Summary Tape File 1) and STF3 (Summary Tape File 3); the former contains the 100% count and the latter contains the sample data. Unlike the 2000 census, the 1990 summary tape files are subdivided into different units. For example, STF1A contains all of the 100% count data down to the block group level, while STF1B contains a subset of the 100% count data down to the block level.
Census data is compiled and distributed by the U.S. Census Bureau, a division of the U.S. Department of Commerce. The WAGDA geodatabases were constructed using the Washington State extracts of the census data held by the Center for Social Science Computation and Research (CSSCR) at the University of Washington. Each county-level database contains all of the SF1 and SF3 data for all geographic summary levels within the county. The data is in its original form and has not been modified in any way. The state-level geodatabases only contain data at the county, metropolitan area, place, tract, and 5-digit ZIP code tabulation area levels.
Boundary files included in the database are originally from the Census Bureauís TIGER Line File Extracts for Washington State. WAGDA obtained these files from the State of Washington Office of Financial Management (OFM) in ESRI shapefile format. The OFM had modified the files by adding attributes and metadata, and had projected the data in GCS_North_American_1983_HARN.
WAGDA reprojected the files to NAD_1983_HARN_StatePlane_Washington_North_FIPS_4601_Feet and imported the shapefiles into a geodatabase. Technically, two of the counties (Thurston and Pierce) are actually located in the Washington State Plane South zone, but for the sake of consistentcy WAGDA has projected all of the boundaries in State Plane North - users can always reproject the data using the Projection Tools in the ArcToolbox. WAGDA also created additional versions of each of the census geography files (tracts, block groups, and blocks) where the boundaries do not incorporate water. This was achieved by clipping each of the census boundaries based on water boundaries. Geographic metadata (created by the OFM) for each of the boundaries can be viewed within the ArcCatalog.
In some instances, the boundary files from the OFM required additional modification in order to be incorporated in the geodatabases. The boundary file for cities and census designated places was created by merging the OFM's city limit boundaries and designated places files into one file. The TYPE field in the attribute table indicates the file that each geographic area originally came from: CITY or CDP. The boundary file for metropolitan areas was created by selecting and aggregating counties from the OFM's county boundary file, based on the Census Bureau's 1999 definition of metropolitan statistical areas.
The 5-digit ZIP Code tabulation area boundaries were the only boundary files not obrtained from the OFM, as this layer was not available from that source. The ZIP boundaries were downloaded from the Census Bureau's Generalized Cartographic Boundary File web page in ESRI shapefile format, and were originally projected in UTM. Since this is a generalized layer, the boundaries do not correspond exactly to the boundaries provided by the OFM. ZCTA's were not used in the 1990 census and are not included in the 1990 geodatabases.
The geodatabases are in ESRI File geodatabase. Geospatial processing was conducted using ArcGIS 10.0.