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Mapping the Data Subject Matter Items Data Access: Register Using the Data Maps; Locating Tracts About Census Tracts Geodemographics WebCourse |
Census Tract Demographics -- information resources for census tracts on population, households, families & income
2008 Quarterly Census Tract Estimates Use census tract demographics, accessible via this Web page, for applications such as determining eligibility and application for participation in Federal, state, and local government programs. Apply these data resources to meet your compliance reporting and analyses that require census tract demographics. Use the census tract demographics for other, wide ranging, research and analysis applications. Reasons for widespread use of census tract demographics result in part from the more extensive scope of subject matter available from the decennial census for census tracts than for other smaller area geographic tabulation levels (block groups). Also, census tracts are small, on average 4,000 population, but census tract estimates have a relatively smaller estimation error than do smaller geographic areas such as block groups. The approximately 65,000 census tracts covering the U.S. wall-to-wall provide a good geographic granularity to meet many needs. Unchanging throughout the decade, census tract and census block group (census tract subdivisions) boundaries are subject to update for each decennial census. Many census tract and block group boundaries will remain unchanged for Census 2010. See the Census 2010 census tract and block group final criteria descriptions. Using CommunityViewer to Create Census Tract Thematic Maps See Using CommunityViewer to Build Census Tract Maps for a step-by-step description on how you can use the no-fee CommunityViewer software to create maps of small areas selecting from thousands of demographic subject matter items. The remainder of this page is a 'legacy' summary of accessing and using census tract data without using the CV software. Scope of Available Data The census tract demographics provided via this document are focused on enabling the analysis of low income population census tracts and related income measures. These data files have been developed by Proximity and are based on Census 2000 Summary File 3 data. These data are organized as zip files which are expanded into dbase 4 structured files. Files are available for each state and D.C. Each state file contains a data record for each census tract in the state. Source and Extended Information Resources. Data provided via this Web page are a subset of the Proximity database and information service. A wider range of subject matter is available from the Proximity database. Resources to Make Thematic and Reference Maps. You can also create thematic maps, such as the one shown at the top of this Web page, for any location in the U.S. Proximity has developed a national and state-by-state census tracts geodemographics in shapefile structure. To see how these applications can operate on your computer, download the Hawaii state by census tract geodemographics zip file. Expand this file into the folder c:\tracts and then use the CommunityViewer software to view the data in the form of thematic or reference maps. Installing application on your computer ... 1 - Install CommunityViewer software on your computer 2 - Expand the Hawaii by Census Tract Map Project and Shapefile zip file to c:\tracts folder The dbase file associated with the shapefile set, in item 2 above, contains the - DP2 subject matter items (http://proximityone.com/dp2.htm), - DP3 subject matter items (http://proximityone.com/dp3.htm), and - total population, total housing units and other selected items. Users of the shapefile, referenced in item 2 above, should refer to these web pages for the description corresponding to shorter item names used in the dbase file. These same data are available from Proximity in census tract shapefile structure for any area in the U.S. • Start CommunityViewer • File>Open>c:\tracts\hitracts.gpr For more information on accessing the broader data in Proximity databases or acquiring the map files, contact Proximity. Subject Matter Items [goto top] The table presented below summarizes the scope of subject matter items contained in each census tract data record.
Data Access: Registration for Data Access and Use [goto top] Single state files are available on a no fee basis. To obtain the census tracts demographics file, complete the registration form. Files are e-mailed to registrants using the e-mail address provided in the registration form. Using the Data [goto top] This section reviews steps that can be followed to use these data. The role of mapping and thematic maps is referenced in this page, but usage instruction is beyond the scope of this page. Participate in the Geodemographics WebCourse to learn more about using these tools, data, and methods. Download the zip file and expand into a folder such as c:\tracts. The file may then be opened with any software that can process a generic dbase 4 structured file. Application 1 - Profile for One Census Tract. The following text and graphics illustrate how spreadsheet software can be used to convert data in the dbase file into a profile for a census tract or a group of census tracts. In this application, the tractshi.zip file for Hawaii is used (expands to tractshi.dbf). (The file tracts.xls used in the next set of steps is already preloaded with the answer that you will get as you go through the steps.) Proceed with the following steps to yield the graphic shown in Figure 1.
Figure 1. Spreadsheet Section 1 [goto top] 
Results, continued. In the lower portion of the spreadsheet, as shown in Figure 2, it can be observed that there are 15.38-percent of all families who have income that is below the poverty level income in 1999. Similarly, it can be observed that there are 32.85-percent of families with a female householder, no husband present, that are below the poverty level in tract 38. More in general, the steps outlined above have resulted in creating the percentage distributions that appear in rows 33 through 45. Figure 2. Spreadsheet Section 2 [goto top] 
Application 2 - Analysis Across Tracts in a County/Region. Rather than profiling one census tract, or a set of tracts, interest might focus on analysis across census tracts. In the following application, the census tracts are ranked by those with highest percent with female householder, with no husband present, for Honolulu County (county code 003). Using the file tractshi.dbf with Excel, proceed as follows:
Figure 3. Spreadsheet Cross Sectional [goto top] 
Maps and Locating Tracts Locating tracts of interest in a state file. You might have interest in only a portion of a state, such as a county or metropolitan area. Use the geographic identifier codes to select only those parts of the state file of interest in such cases. County names are not included in the census tract demographics files. To locate census tracts in a set of counties of interest, you need to know the county code for the county(s). The county code field in the database is shown as FIPS County Code. One way to get the FIPS County Code (a three digit code with leading zeroes) is to use the code-name equivalency list located at http://www.census.gov/geo/tigerline/apendx_a.txt. Similarly, metropolitan area names are not included in the files. However, the MSACMSA, CMSA, PMSA, or NECMA code(s) can be used to select tracts in metropolitan statistical areas of interest. Get these code(s) for your areas of interest from the list provided at http://www.census.gov/population/estimates/metro-city/a99mfips.txt. Viewing the boundaries of census tracts. Given that you have a set of census tracts codes, possibly a list such as shown in Figure 3, there are several map options that can be used to view where these tracts are located.
Census tracts in the U.S., Puerto Rico, and the Virgin Islands generally have between 1,500 and 8,000 people, with an optimum size of 4,000 people. For American Samoa, the Northern Mariana Islands, and Guam, the optimum size is 2,500 people. Counties and statistically equivalent entities with fewer than 1,500 people have a single census tract. Census tracts on American Indian reservations, off-reservation trust lands, and special places must contain a minimum of 1,000 people. (Special places include correctional institutions, military installations, college campuses, worker dormitories, hospitals, nursing homes, and group homes.) When first delineated, census tracts are designed to be relatively homogeneous with respect to population characteristics, economic status, and living conditions. The spatial size of census tracts varies widely depending on the density of settlement. Census tract boundaries are delineated with the intention of being maintained over many decades so that statistical comparisons can be made from decennial census to decennial census. However, physical changes in street patterns caused by highway construction, new developments, and so forth, may require occasional boundary revisions. In addition, census tracts occasionally are split due to population growth or combined as a result of substantial population decline. Census tracts are identified by a four-digit basic number and may have a two-digit numeric suffix; for example, 6059.02. The decimal point separating the four-digit basic tract number from the two-digit suffix is shown in the printed reports and on census maps. In computer-readable files, the decimal point is implied. Many census tracts do not have a suffix; in such cases, the suffix field is either left blank or is zero-filled. Leading zeros in a census tract number (for example, 002502) are shown only in computer-readable files. Census tract suffixes may range from .01 to .98. For the 1990 census, the .99 suffix was reserved for census tracts/block numbering areas (BNAs) that contained only crews-of-vessels population; for Census 2000,the crews-of-vessels population is included with the related census tract. Census tract numbers range from 1 to 9999 and are unique within a county or statistically equivalent entity. The Census Bureau reserves the basic census tract numbers 9400 to 9499 for census tracts delineated within or to encompass American Indian reservations and off reservation trust lands that exist in multiple states or counties. The number 0000 in computer-readable files identifies a census tract delineated to provide complete coverage of water area in territorial seas and the Great Lakes. About Proximity. Proximity provides services that include developing, organizing, analyzing, and interpreting decisionmaking data for a region, community, market/study area or a group of areas. Proximity develops data, software and data access/integration infrastructures to assist businesses, academia, government agencies, associations, and others implement solutions to meet information needs and solve problems. goto top | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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