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Census 2000: Census 2000: The Redistricting Summary Data (Public Law 94-171)
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Census 2000: The Redistricting Summary Data (Public Law 94-171)

Jan 17, 2016

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  • Census 2000: The Redistricting Summary Data (Public Law 94-171)

  • Redistricting Data ProgramPublic Law 94-171 enacted in 1975Outgrowth of 1960s court decisions on One-Person/One-Vote and 1965 Voting Rights ActState legislatures can receive data according to local definitions to ease planning new district boundariesFirst look at racial/ethnic profile of local community

  • Data Items IncludedTotal PopulationHispanic/Latino OriginRaceVoting Age Population

  • Public Law 1 (PL1) Data Table: Race

  • Public Law 2 (PL2) Data Table: Hispanic or Latino, and Not Hispanic or Latino by Race

  • Public Law 3 (PL3) Data Table: Race for the Population 18 Years and Over

  • Public Law 4 (PL4) Data Table: Hispanic or Latino, and Not Hispanic or Latino by Race for the Population 18 Years and Over

  • Office of Management and Budget Race CategoriesAmerican Indian or Alaska NativeAsianBlack or African AmericanNative Hawaiian or Other Pacific IslanderWhiteSome other Race-----------Two or More Races

  • Race Items of InterestRespondents could choose more than one categoryTotal possibility of 63 racial categoriesHispanic/Latino origin cross-tabulation equals 126 possible racial/ethnic categories In a National Content Survey on Race in 1996, 1.2% reported multiracialIn 1998 Dress Rehearsal, 5.4% of Sacramento, Ca. respondents were of multiple races

  • Maximum Combination of Six Racial Categories 6 racial categories+57 combinations of two or more races 63 Possible combinations

  • Two or More RacesCategory where all multiple-race responses are grouped togetherThis category, together with the 6 single-race alone categories, will add up to 100% of the populationThe result is that direct comparisons back to 1990 racial categories CANNOT be made

  • Population Data Summary Levels In Public Law 94-171 FileCountiesCounty subdivisionsPlaces (incorporated and census designated)Census tractsCensus block groupsCensus blocksVoting districts*State house and state senate districts** - where provided

  • Census Geography Overview

  • Data AccessibilityData provided to states on CD-ROM, with software to view, print, download itemsDelivered by April 1, 2001 to governor, majority/minority legislative leadersCensus Maps /TIGER/Line files delivered to state officials prior to March 1, 2001P.L. 94-171 redistricting data publicly accessible on www.census.gov

  • Accessibility MethodsFile Transfer Protocol (FTP)For downloading complete dataset filesWill be available at http://ftp2.census.govAmerican FactFinderQuick TablesGeographic Comparison TablesDetailed TablesCD-ROMsMaps, TIGER/Line

  • Media Type: FTP vs AFF vs CD-ROMFTPAFFCDDifficultyHighLowLowCostNoNoYesUser LevelHighAllAllSpeedVariableVariableHighConnect IssuesPossiblePossibleUnlikelyDownload limitsNone5 megsCD sizeGraphical User InterfaceNoneYesYes

  • http://ftp2.census.govBegin by selecting the file you want to downloadThen save the file down to your PC

  • Using your Windows Explorer open the zipped filesUse unzip software available for free at www.winzip.com or www.pkunzip.com

  • Geographic Comparison TablesQuick TablesData Sets

  • Downloading Data in American FactFinder

  • Redistricting Summary Data CD-ROM

  • Maps and TIGER/LineThree map types in three formatsCensus Tract OutlinePaper (8.5 x 11), PDF off the web, HPGL on demandVoting District Outline MapsVoting district outline (no state legislative district) on Paper, PDF off the web, and HPGL on demandCounty Block MapsIncludes voting district and legislative district boundaries and codesPaper, PDF off the web, and HPGL on demand

  • Census Tract Outline Maps

  • Voting district/state legislative district outline maps

  • County Block Maps

  • TIGER/Line FilesFirst TIGER/Line File to contain final Census 2000 tabulation geographyLegal areas with January 1, 2000 boundariesCensus 2000 statistical areas (tracts, CDPs)Voting districts/legislative districtsTabulation census blocks

  • For More Informationwww.census.govStrength in Numbers: Your Guide to Census 2000 Redistricting Data From the U.S. Census Bureau - brochureWhat You Should Know About the Apportionment Counts - brochureCustomer Service Center (301) 457-4100webmaster@census.gov

    U.S. Supreme Court decisions in the 1960s clarified the Constitutions intention to provide equality of representation for all Americans.

    These Supreme Court decisions increased the states needs for geographically detailed census information in the redistricting process. Redistricting is the redrawing of legislative district boundaries based on population changes. The urgency of the states need for these data led Congress to pass Public Law 94-171 in December 1975.

    The data provided under the provisions of Public Law 94-171 enable the states to redraw legislative boundaries. The Redistricting data provide data users with a first look at Census 2000 results for their communities as well as the local racial/ethnic demographic makeup.

    Optional Notes on details of Redistricting programPL 94-171 sets up a voluntary program between the Census Bureau and those states that wish to receive population tabulations for election precincts and other state specified geographic areas. Under this 3-phase program, those responsible for the legislative apportionment or redistricting of each state may devise a plan identifying the voting areas for which they want the specific tabulations and submit them to the Census Bureau. 46 states participated in some fashion in Phases 1 and 2 of this program so far. 4 States that did not participate: Florida, Kentucky, North Dakota, South DakotaNOTE: Puerto Rico was not included in this programThe data items included in the PL 94-171 tabulations are from the limited number of short form items that are asked of all households, that is, age, sex, race, and Hispanic origin.

    PL 94-171 specifically requires total population counts. However, since the 1980 census, the Census Bureau has included summaries for the major race groups, the Hispanic-Latino-origin population, and for the Non-Hispanic or Latino population by race.

    Beginning with the 1990 census, at the request of State legislatures and the Department of Justice, voting age (18 years and over) was added to the cross-tabulation of race and Hispanic origin.

    Now well see examples of the four PL data tables. This is the Public Law 1 Data Table for Race. Here we see the multiple race categories broken out. Note the (71) in parenthesis at the top of the table [and varying in other tables] indicates the number of data items. This is the Public Law 2 Data Table; Hispanic or Latino, and Not Hispanic or Latino by Race. Please note that Hispanic or Latino by race is not provided. It can be derived, however by subtracting the Not Hispanic or Latino population by race in this table (PL2) from the total population by race in the first table (PL1). This is the Public Law 3 Data Table; Race for the Population 18 Years and Over.[Otherwise known as the Voting Age table] This table is similar to PL1 except for the Voting Age universe difference.To obtain the Under 18 population you will have to subtract PL3 from PL1.This is the Public Law 4 Data Table; Hispanic or Latino, and Not Hispanic or Latino by Race for the Population 18 Years and Over. This table is similar to PL2 except for the Voting Age universe difference.

    This leads us into a discussion on the newly defined categories of race groups for Census 2000. The Federal Office of Management and Budget (OMB), based on input from Federal Agencies, groups, and individuals, specifies how Federal Agencies should collect and tabulate data by race. The OMB recognized, particularly since the 1990 census, that the existing categories did not reflect our Nations increasing diversity. In 1997, after a lengthy analysis and public comment period, OMB revised the guidelines for data by race. [OMB reference: http://whitehouse.gov/omb/inforeg/race.pdf] This revision provided for the following changes:1) It divided the earlier Asian/Pacific Islander category into:AsianNative Hawaiian and Other Pacific Islander2) Respondents could mark one or more categories to self-identify their race3) A separate question is to precede the race question to allow respondents to indicate whether or not they identify as Hispanic\Latino

    With permission from the OMB, the Census Bureau included the category Some other Race on the Census 2000 questionnaire.Optional Speaker Note: OMB determined that Alaska Native should replace the term Alaskan Native and that Alaska Native should be used instead of Eskimo and Aleut. Additionally, The Alaska Native response option should be accompanied by a request for a tribal affiliation write-in.

    Responding to the changing demographics of the American public, Census 2000 is the first time respondents have been able to select more than one race.

    Moreover, Hispanic/Latino origin is not considered a race and is asked separately, before the race question on the Census 2000 questionnaire.

    So, these new methods of collecting racial and Hispanic responses have resulted in 63 possible race combinations, which when cross-tabulated by Hispanic/Latino or Non-Hispanic/Latino, results in a grand total of 126 different racial/ethnic combinations.

    In a 1996 National Content Survey on Race conducted by the Census Bureau, among many findings, it was reported that 1.2% of respondents reported as multiracial. Following that effort up, in the 1998 Census Dress Rehearsal, the percentage of people who actually did check off two or more races across the several test sites was not very high.[Sacramento, 5.4%; several counties in South Carolina, 0.8%; Menominee, Wisconsin 1.2%] While only representing a small group, multiracial tabulations of the races adds new complexity to the many data items users have as resources to make decisions. Here is a mathematical equation illustration of the 6 racial categories that stand alone (One Race Alone) in addition to the various combinations of the two or more races category.

    Optional Speaker notes on number of unique possible combinations:15: Two races in combination20: Three races in combination15: Four races in combination6: Five races in combination1: Six races in combination 57 Total combinationsThe most important issue on this slide is the fact that users need to understand that direct comparisons in racial categories from 1990 to 2000 CANNOT be made. Since respondents were able to check more than one race, a decision must be made by the individual data user or organization using the data whether to use a single race alone figure or the race alone or in combination figure. The Census Bureau will NOT be developing direct bridges back to 1990 Census data or categorizations. When the Census Bureau releases the Redistricting Summary Data publicly, the accompanying press release will have some tables and dialogue largely devoted to explaining to users exactly what past comparisons can be made and what assumptions they should be coupled with. These are the various levels of geography for which data are available on the Public Law File. For a brief explanation of Census Bureau geography, the next slide contains a graphic illustrating how these pieces fit together.

    NOTE: * - Only where states provided it to the Bureau in 1999. These were districts that were used in the 1998 elections (106th Congress).

    For Census 2000 the entire nation was divided into blocks and census tracts. There are no longer any enumeration districts or block numbered areas. In Census geography, we start with the most basic unit, the Census Block. The Census Block on average has about 100 persons in it. In urban areas a Block can be a very small physical area, yet in rural areas Blocks can span hundreds of square miles. Blocks are usually placed into Block Groups which optimally consist of about 1,500 persons, but can max out at 3,000 persons. Moving up the line, several Block Groups usually fit into a Census Tract which optimally consists of 4,000 persons but can range between 1,500 to 8,000 persons.

    Continuing up in the Census hierarchy are places , including incorporated places-that is-legally incorporated governmental entities with a mayor and other offices. There are also Census Designated Places (CDPs) that are closely settled, named, unincorporated communities that generally contain a mixture of residential, commercial, and retail areas similar to those found in incorporated places of similar sizes. CDPs do NOT necessarily have to follow minimum or maximum population guidelines. Minor Civil Divisions (MCDs) or Census County Divisions (CCDs) are used to establish and maintain a set of subcounty units that have stable boundaries and recognizable names. 21 States have CCDs and 28 States have MCDs; they do NOT necessarily have to follow minimum or maximum population guidelines. A CCD usually represents one or more communities, trading centers or, in some instances, major land uses. An MCD is a type of governmental unit that is the primary legal subdivision of a county, created to govern or administer an area rather than a specific population.(ex. Town, Township, District) Many MCDs represent local general-use government units, which makes them required areas for presentation of decennial census data.

    By law, the redistricting data must be delivered to the states by April 1, 2001. These data include total population and population 18 years and over by 63 race categories, non-Hispanic population for the same race categories and Hispanic or Latino population for all levels of geography down to the census block.

    PL data are released in the following sequence of events. First, the data are provided to the government entities (majority and minority legislative leaders, governors, etc.). After a brief period, the data will then be available to the public via the American FactFinder online data retrieval tool available from the Census Bureaus web site at www.census.gov. Then, after allowing for production, CD-ROMs containing the data will be available for purchase through our on-line Catalog. Data are released on a state by state basis on AFF and then CD-ROM. Once all states have been released the entire country will be available on DVD-ROM (3 discs). After that, a nation-wide single CD-ROM product will be released, containing data down to the county/place level.

    Maps and geographic files are provided to state officials prior to the release of the data and are available to the public shortly thereafter.Local officials needing the data for redistricting purposes and other data users can find virtually everything they need off the Census Bureaus web site, www.census.gov.

    American FactFinder will have all the PL data down to the block level. You can look at tables for various geographic areas. There will be a special site for file transfer protocol downloading of complete data sets in ASCII Comma Delimited. (The Census Bureau recommends purchasing a CD-ROM through the on-line product catalog at www.census.gov if downloads larger than 3-5 megabytes of data will be needed). Electronic copies of all the PL maps provided to officials will be available on-line by April 2001TIGER/Line files for plotting maps on your Geographic Information System software programMaps will be available for purchase through a print-on-demand service. For more information call our Customer Services Center at 301-457-4100.

    Now lets take a closer look at the 3 ways youll be able to get the information:- File Transfer Protocol- American FactFinder- CD-ROMHere we see a matrix that gives the pros and cons of each method of accessing Census 2000 data. Briefly, the FTP method is designed solely for experienced data users who have a vast knowledge of complicated downloads involving segmented files. American FactFinder is an easy-to-use, free data tool that all users will find helpful. AFF is subject to some download limitations though. Purchasing CD-ROMs will keep users from having to be on-line to download large amounts of data. The CD-ROM has a Graphical User Interface (GUI - basically the windows usability format) with preformatted tables, in addition to the raw data files available for download.

    Now well take a closer look at File Transfer Protocol.To get to this FTP site, click on Redistricting from the main census site at www.census.gov. Then on the Redistricting main page, in the left hand column will be a tab labeled File Downloading (FTP Server).

    Once you click on that you will be brought to this screen. We start at the http://ftp2.census.gov site and work our way through the file manager tree to the exact file wed like to download. Once the desired file is selected, the data can be saved to your local PC in a compressed or Zipped format. You will need to have software on your PC that can unzip these compressed files in order to see the full data set.

    NOTE: Data files are all in ASCII comma delimited format. As a clarification the tfgeo.uPL.zip file is in a fixed file format, while the two other data files are in the ASCII comma delimited format. The READ file that is included in the ftp files contains useful background information on FTP. It also includes megabyte estimations of each states total file size. On the low end is D.C. at 3 megabytes up to Texas at 310 megabytes. As mentioned earlier, AFF should not be considered for downloads of larger than 5 megabytes.

    Once the file has been downloaded to your local PC, you can unzip the file by using the free software from either www.winzip.com or www.pkunzip.com. Also available in the data file management tree is some technical documentation that can help you make sense of the raw data once it is unzipped. You can either view the data raw in the ASCII Comma Delimited format, or load it into a statistical package that you can use to manipulate the data such as Microsofts Excel spreadsheet.

    Now we will show you how to use the Census Bureaus on-line data retrieval tool, American FactFinder, to find the data you need through a more user-friendly, web-based Graphical User Interface. Here you will see the Main page on American FactFinder. PL data will be the default in AFF Quick Start tables.From this page, you can access the data through multiple means:The Basic Facts section (Start) presents frequently requested data from both population and economic surveys. This area was designed to allow easy access to census data for anyone who can use the internet. Quick Tables and Geographic Comparison Tables, and Detailed Tables are accessible in the lower left-hand area under FactFinder Data Sources Data Sets which are directly available from the left-hand column Search which is available in the top right hand corner

    Now we will take a more detailed look at some of these areas. Geographic Comparison tables provide basic measures for 100-percent and sample population and housing subjects. Users can compare data across geographic areas in the same table (e.g., all counties in a state).

    Quick tables contain fixed presentations of the 100-percent and sample population and housing subjects, and users have the option of selecting a specific geographic area and population group (e.g., White, Black or African-American, etc). Data are available for the U.S., regions, divisions, states, counties, county subdivisions, places, census tracts, metropolitan statistical areas, urban areas, American Indian and Alaska Native areas, tribal subdivisions, Hawaiian home lands, congressional districts, and ZIP Code tabulation areas.

    By accessing the Data Sets directly, users can access Geographic Comparison Tables, Quick Tables, Detailed Tables and Thematic Maps from the same selection area. Data Sets also allows selection of lower level geographies including census tracts and voting districts. Selection methods are the same as for the quick links, but more data are available.

    Now well see how to download tables in AFF.Downloading data from AFF is relatively easy. Go up in the top right hand corner under the Print/Download button of whatever table you are at and select the Download option. Simply pick one of the two available format options [comma delimited (.csv) or tab delimited (.txt)] and save the table down to your PC drive. After the file has saved, using Windows Explorer, you can open the file and it will be formatted in the same tabular view you saw on AFF, only it will be brought up as a spreadsheet. It is important to note that we are showing how to download TABLES in AFF, NOT how to download raw data files. For raw data files, its best to go back to the FTP site or purchase a CD-ROM through census.gov.

    Now well take a look at the CD-ROM product. (In this case the Demonstration Disc)Now we will move on to a demonstration of the CD-ROM data product.

    The CD-ROM comes with an installation guide, technical documentation, and the raw state data files which can be downloaded en masse to a spreadsheet application. All this is in addition to the preformatted data tables available through the Windows-based Graphical User Interface (GUI), for easy access to the state information. Again, the Census Bureau encourages users to purchase the CD-ROM when downloading large state files for example. Heres an example of what the data will look like on the CD-ROM. This is a screen shot from the PL Demonstration CD-ROM showing the Census 2000 Dress Rehearsal data in Sacramento County, Ca. by census tract.

    In the next screen shot we will see detailed information for Tract 0001, Sacramento County, by clicking on the More Detail button at the top of the screen.

    NOTE: The far right 11th column, Hispanic or Latino (of any race) category is not added in to get the total population. It is a stand alone category denoting the Hispanic population across all races. Detailed Race DataDetailed Race data can be found by selecting the applicable geography (in this case Sacramento, Ca census tract 0001), clicking on the More Detail button from the prior screen, then selecting the Detailed Tables tab from this screen.Here we see how to download specific data from the CD-ROM into 5 different formats:ASCIIASCII delimiteddBASEAccessHTML

    Instructions for Downloading:To open the copy window, click the Copy control on the main window.Select the items from Items available to copy and click Select. These items appear under Number of items selected.Check the record layout and technical documentation box to create a Documentation File.Click OK to process data selected. To save your selection, choose File|Save As from the menu bar.

    Now well move on to Census geographic products.To be able to use the Redistricting data file, youll need a map. There are 3 series to choose from depending on what level of geography you want to work with. The Census Bureau estimates that for the Census 2000 Redistricting Data Program nationwide we will produce:75,000 unique county block maps15,000 unique voting district/state legislative district outline map12,000 census tract outline mapsCensus Tract Outline MapThe Census Tract Outline maps show the boundaries and the underlying features (roads, railroads, rivers, county lines, etc.) that make up the boundaries of census tracts. They do not display the entire street grid within a tract.

    Map Legend:Thick Peach lines represent Census Tract boundariesLarge Auburn numbers are the Census Tract numbers

    NOTE: Maps derived from 1998 Dress Rehearsal products in Sacramento, Ca.Voting District/State Legislative District Outline MapsCover a county or equivalent area and show the outline of voting districts and state legislative districts (if defined). These maps provide a quick picture of areas that can be used as a reference as you construct new legislative districts. These maps will also show the boundaries of the current state legislative districts (if the state chose to provide them during phase 2 of the Redistricting Program-the Voting District Project).

    Map Legend:Thick Peach lines represent Voting District boundariesLarge Auburn numbers are the Voting District numbers

    NOTE: Maps derived from 1998 Dress Rehearsal products in Sacramento, Ca.County Block MapsThe Block Maps, the most detailed maps that the Census Bureau publishes, show the Census 2000 tabulation block, block group, and census tract boundaries and codes. They also display boundaries for townships, counties, American Indian areas and incorporated places.

    Map Legend:Blue triangles represent Voting District boundariesBlue numbers are the Voting District numbersThick Peach lines represent Census Tract boundariesLarge Auburn numbers are the Census Tract numbers Thin Peach lines represent Block boundariesSmall Auburn numbers are the Block numbers

    NOTE: Maps derived from 1998 Dress Rehearsal products in Sacramento, Ca.

    As mentioned earlier, local area maps will be mailed to the local area officials for use with redistricting, etc.TIGER/Line files, that became available in January 2001, are the public, accessible version of the Census Topologically Integrated Geographic Encoding and Referencing (TIGER) system. This system contains legal and statistical geographic areas and codes, and the underlying street network. By obtaining these files along with the statistical data files, you can plot thematic maps using Geographic Information Systems (GIS). This will allow you to quickly determine the impact on the demographic makeup of a district when you move a boundary. These files are not graphic images of maps, but rather digital data describing geographic features. NOTE: These files will be available in a 7 CD-ROM set (compressed files). Uncompressed, the Nation is about 30 gigabytes of data.

    Speaker NOTE: Maps will be available:Paper copies in February 2001HP-GL on DVD in March 2001 (large plotted maps)PDF on CD-ROM and Internet in April 2001Boundary Files will be available in April 2001

    The Census Bureau has CD-ROMs, DVD-ROMs, Printed Reports, Maps, and other various data resource media are available for free on our internet site at www.census.gov. These products are also available for purchase. For ordering information go to the Catalog on the left hand column of the census.gov site.As mentioned before, the online data retrieval system, American FactFinder will be the one source for all Census 2000 data that becomes available.Users with questions should call the Customer Service Center, 301-457-4100.

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