README File for /0File_Structure
The structure of the three files provided for each state Redistricting Summary File product is documented in the file, 0README_PL, found under each state directory, for example: http://www2.census.gov/census_2000/datasets/redistricting_file--pl_94-171/Alabama/0README_PL.doc.
Microsoft Access 97 and Microsoft Access 2000 files contain import specifications describing the fixed-field format of the geographic header and assign names to each of the data elements included in the three Redistricting Summary Files. These datasets were created to support testing of the FTP application. For Windows users, these files can reduce the burden of preparing an environment in which to work with these Redistricting Summary Files. The Access and xBASE files are stored in subdirectories of this directory named Access97/, Access2000/, xBase/, and SAS/ respectively. These files are made available on an as-is basis.
The following xBASE files are provided:
The Access databases, PL2000.mdb, contain the following tables:
Header (corresponds to HEADER.DBF)
PL_Geo_Header (corresponds to PL_GEOHD.DBF)
PL_Part1 (corresponds to PL_PART1.DBF)
PL_Part2 (corresponds to PL_PART2.DBF)
Tables (corresponds to TABLES.DBF)
The following SAS files are provided:
pl_geohd.sas (produces a GEO header data set)
pl_part1.sas (produces a table 1 and 2 data set)
pl_part2.sas (produces a table 3 and 4 data set)
pl_all_3.sas (puts all 3 PL files together in 1 data set)
Users of these SAS files will have to modify the libname, data, and infile statements to confirm to their environments. The pl_all_3.sas file is merged by LOGRECNO. Users should check their SAS log for inconsistencies. These programs have been tested using SAS version 8.
For Access Users
The following are suggestions for loading the Redistricting Summary Data into an Access database:
Download the compressed files from the FTP site.
Uncompress the PL files you wish to load into Access. For convenience, you may want to place these files in a clearly named subdirectory. (NOTE: The files downloaded from the FTP site were created in a UNIX environment. To work with these files in a Windows environment you must uncompress the data sets using compression software that can convert the format of these files to a DOS/Windows compatible format (ASCII line feed to carriage return with line feed conversion). See the 0README file accompanying the data sets.)
Make a copy of the downloaded .mdb file in the subdirectory where you want the new Access database to reside. Rename the copy (for example, MyPLData.mdb).
Select and open the new database you created (for example, MyPLData).
From the File menu, select Get External Data/Import.
In the Import window, (a) select Text Files for Files of Type, (b) enter *.* for File name, (c) select the subdirectory where the uncompressed files were placed to complete the "Look In" option, (d) select the file you want to import (for example, AKGEO) and (e) press the Import button.
In the Import Text Wizard window, click on the Advanced option. In the Import Specification window, click on Specs. Select the appropriate import specification. (There is an import specification for each of the three PL file types.) Click Open. Then click OK.
In the Import Text Wizard window, click Next twice. Select In a New Table. Click Next a third and fourth time. Select Choose My Own Primary Key. Select LOGRECNO. Click Next. Change the name of the Access table if you wish. Click Finish.
Repeat part 2 until all three files for a state have been added.
The structure of the files is identical in each format. These three files provide file structure only. They contain no data. The structure of each is detailed below:
The remaining files, HEADER and TABLES, contain additional metadata that can be used to understand the content of the Redistricting Summary Files. The content of those two files is as follows: