Each redistricting dataset merges the electoral data the SWDB collected and processed over the preceding decade with the most current census data (PL94-171). The result is a census block level dataset that allows for longitudinal analysis of electoral data over time on the same unit of analysis. Electoral data consist of the Statements of Vote (SOV) and Statements of Registration (SOR) for each statewide election. These data are collected from the Registrars of Voters for each of the 58 California counties with each election.
The SWDB collects the Statement of Vote and the Statement of Registration along with various geography files from each of the 58 counties for every statewide election. The Statement of Vote is a precinct level dataset and precincts in California change frequently between elections. The goal of the SWDB is to make election data available that can be compared over time, on the same unit of analysis – a precinct, a census block or a census tract.
Due to a large number of questions on how to use the PL 94-171 data, we have repackaged the census data for ease of use in GIS applications. Below you will find tract-level and block-level datasets for all of the PL 94-171 variables in tables 2, 4 and H1.
The files are zipped DBF tables, so you can import them into any popular GIS software. The files contain variables from the PL tables, as well as the following geographic identifiers: COUNTY, PLACE (block file) only, TRACT, BLOCK, BLOCK_KEY (block file only) and TRACT_KEY (tract file only).
The BLOCK_KEY field should be used to join the tables to a block-layer geography and the TRACT_KEY is used to join the tract tables to a tract-layer geography.
Codebook for description of the fields.
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