2018 General Election Results Disaggregated to 2020 Census Blocks for Texas

## RDH Date retrieval
11/16/2022

## Sources
Precinct shapefile with election results retrieved from the Redistricting Data Hub[https://redistrictingdatahub.org/]
Precinct shapefile with election results is originally from the Voting and Election Science Team (VEST)[https://dataverse.harvard.edu/dataset.xhtml?persistentId=doi:10.7910/DVN/UBKYRU].
Block shapefiles and data are retrieved from the Redistricting Data Hub[https://redistrictingdatahub.org/dataset/texas-block-pl-94171-2020-by-table/] and originally from the Census Bureau's Public Law 94-171 dataset and TIGER shapefiles.

## Fields metadata

Vote Column Label Format
------------------------
Columns reporting votes follow a standard label pattern. One example is:
G20PRERTRU
The first character is G for a general election, C for recount results, P for a primary, S for a special, and R for a runoff.
Characters 2 and 3 are the year of the election.
Characters 4-6 represent the office type (see list below).
Character 7 represents the party of the candidate.
Characters 8-10 are the first three letters of the candidate's last name.

Office Codes
A## - Ballot amendment, where ## is an identifier
AGR - Commissioner of Agriculture
ATG - Attorney General
AUD - Auditor
CFO - Chief Financial Officer
CHA - Council Chairman
COC - Corporation Commissioner
COM - Comptroller
CON - State Controller
COU - City Council Member
CSC - Clerk of the Supreme Court
DEL - Delegate to the U.S. House
GOV - Governor
H## - U.S. House, where ## is the district number. AL: at large.
HOD - House of Delegates, accompanied by a HOD_DIST column indicating district number
HOR - U.S. House, accompanied by a HOR_DIST column indicating district number
INS - Insurance Commissioner
LAB - Labor Commissioner
LAN - Commissioner of General Land Office
LND - Commissioner of Public/State Lands
LTG - Lieutenant Governor
MAY - Mayor
MNI - State Mine Inspector
PSC - Public Service Commissioner
PUC - Public Utilities Commissioner
RGT - State University Regent
RRC - Railroad Commissioner
SAC - State Appeals Court (in AL: Civil Appeals)
SBE - State Board of Education
SCC - State Court of Criminal Appeals
SOC - Secretary of Commonwealth
SOS - Secretary of State
SPI - Superintendent of Public Instruction
SPL - Commissioner of School and Public Lands
SSC - State Supreme Court
TAX - Tax Commissioner
TRE - Treasurer
UBR - University Board of Regents/Trustees/Governors
USS - U.S. Senate

Party Codes
D and R will always represent Democrat and Republican, respectively.
See the state-specific notes for the remaining codes used in a particular file; note that third-party candidates may appear on the ballot under different party labels in different states.

## Fields
GEOID20 - Block Unique ID
STATEFP - State FIPS Code
COUNTYFP - County FIPS Code
PRECINCTID - Unique Precinct Identifier
VAP_MOD - Modified Voting Age Population (VAP)

G18VR - Voter registration
G18SSVR - Spanish surname voter registration

G18USSRCRU - Ted Cruz (Republican Party)
G18USSDORO - Beto O'Rourke (Democratic Party)
G18USSLDIK - Neal M. Dikeman (Libertarian Party)

G18GOVRABB - Greg Abbott (Republican Party)
G18GOVDVAL - Lupe Valdez (Democratic Party)
G18GOVLTIP - Mark Jay Tippetts (Libertarian Party)

G18LTGRPAT - Dan Patrick (Republican Party)
G18LTGDCOL - Mike Collier (Democratic Party)
G18LTGLMCK - Kerry Douglas McKennon (Libertarian Party)

G18ATGRPAX - Ken Paxton (Republican Party)
G18ATGDNEL - Justin Nelson (Democratic Party)
G18ATGLHAR - Michael Ray Harris (Libertarian Party)

G18COMRHEG - Glenn Hegar (Republican Party)
G18COMDCHE - Joi Chevalier (Democratic Party)
G18COMLSAN - Ben Sanders (Libertarian Party)

G18LANRBUS - George P. Bush (Republican Party)
G18LANDSUA - Miguel Suazo (Democratic Party)
G18LANLPIN - Matt Pina (Libertarian Party)

G18AGRRMIL - Sid Miller (Republican Party)
G18AGRDOLS - Kim Olson (Democratic Party)
G18AGRLCAR - Richard Carpenter (Libertarian Party)

G18RRCRCRA - Christi Craddick (Republican Party)
G18RRCDMCA - Roman McAllen (Democratic Party)
G18RRCLWRI - Mike Wright (Libertarian Party)

G18SSCRBLA - Jimmy Blacklock (Republican Party)
G18SSCDKIR - Stever Kirkland (Democratic Party)

G18SSCRDEV - John Devine (Republican Party)
G18SSCDSAN - R.K. Sandill (Democratic Party)

G18SSCRBRO - Jeff Brown (Republican Party)
G18SSCDCHE - Kathy Cheng (Democratic Party)

G18SCCRKEL - Sharon Keller (Republican Party)
G18SCCDJAC - Maria T. (Terri) Jackson (Democratic Party)
G18SCCLSTR - William Bryan Strange III (Libertarian Party)

G18SCCRHER - Barbara Parker Hervey (Republican Party)
G18SCCDFRA - Romana Franklin (Democratic Party)

G18SCCRSLA - Michelle Slaughter (Republican Party)
G18SCCLASH - Mark Ash (Libertarian Party)

## Processing Steps
Precinct and block shapefiles were retrieved from the sources listed above. The primary libraries used in processing are geopandas, pandas, and maup[https://github.com/mggg/maup] in Python. 
The block data was prepared by creating the VAP_MOD field which is the total Voting Age Population (P0040001) minus Correctional Facility/Prison Population (P0050003) which will be used as the denominator in disaggregation.
The block file was queried out to include just the GEOID20, VAP_MOD, and geometry fields.
To assign blocks to precincts, the maup.assign function was used. Some blocks did not receive an assignment but nearly all of these had a VAP_MOD value of 0, meaning those blocks should not receive any votes during allocation anyway. In the rare instance where there was a block with a VAP_MOD > 0 and no precinct assignment, the L2 voter file was used to determine what precinct assignment was listed for residents of that block in 2020. If no results were returned, the block did not receive an assignment, otherwise the precinct assignment for the block was modified accordingly.
After the blocks have a received an assignment, they are grouped by their new assignment and summed to give a total VAP_MOD value for the precinct. A ratio is then calculated of VAP_MOD block / VAP_MOD precinct, which is applied to all candidate columns (those starting with "G18").
In some instances, there are precincts that sum to 0 for VAP_MOD but do contain votes. In order to not lose votes in the disaggregation process, these blocks are modified to VAP_MOD=1, then summed again to get a non-zero value denominator for VAP_MOD at the precinct. Therefore all blocks in the precinct would have the same ratio applied and receive the same distribution of votes. All blocks that have a modified VAP_MOD value were returned to their original value of 0 before extraction to maintain accuracy.
A key assumption of maup is that a block receives one precinct as an assignment. The RDH checks for any precincts with votes which have not been assigned to any blocks. In these instances, the block file is clipped to each precinct geometry, and the block which has the largest area inside the precinct receives all of the votes from that precinct.

##Additional Information 
For more information please contact info@redistrictingdatahub.org or visit our GitHub[https://github.com/nonpartisan-redistricting-datahub/election-disag]