Revisiting Redistricting in
Texas: A method for
predicting election results
Maddalena Romano
GEOG 596A: Individual Studies
Introduction
Thesis Statement:
Using 2010 election data, I will predict the election results for 2012
for the Texas congressional districts based on the newly-proposed
districts.
Hypothesis:
Similar to the results of the 2004 election, the redistricting effort will
result in more wins for Republicans in the Texas Congressional
Districts.
Goals and Objectives
Goals
•Determine the percentage of voters in the current districts that are
registered Republican voters.
•Determine the Republican Majority in the new districts.
•Predict the number of new districts that will elect a Republican to
the US House of Representatives.
Objectives
•Demonstrate how redistricting is being used so that the party
currently in power in Texas can remain in power.
•Demonstrate how the distinction between redistricting and
gerrymandering are often difficult to determine.
•Determine if gerrymandering alone is enough to explain the results
of the 2012 election.
•Demonstrate how decisions such as these made at the state level
can have repercussions on a national level.
Background
• The Redistricting Process
Background
• The Redistricting Process
• The Politics of Texas
• Battleground Texas
• Nate Silver’s Predictions
• The Modifiable Area Unit Problem
Background
Background
• The Redistricting Process
• The Politics of Texas
• Battleground Texas
• Nate Silver’s Predictions
• The Modifiable Area Unit Problem
• The Voting Rights Act of 1965
Methods
Data, Variables, Assumptions
Data
•Districts:
gis1.tlc.state.tx.us/
•Historical Election Data: elections.sos.state.tx.us/elchist.exe
Variables
•the 2010 number of voters per district
•the 2010 political party with which they are registered
•the 2010 Congressional election results for Texas
•Republican voters
•Democratic Voters
•the 2012 number of voters per district
•the 2012 political party with which they are registered
•the 2012 Congressional election results for Texas
Assumptions
•Voter population is evenly distributed
•Voter turnout is evenly distributed
•Voter turnout can be used as an indicator of the number of Republicans in
a district
•Gerrymandering was a key component of the redistricting process
•Population growth is reflected in the 2010 election results
Exploring the data
Figure 3: 2010 Districts with percentage of Republican Majority.
Exploring the Data
Figure 4: Proposed 2012 Texas Congressional Districts superimposed over Republican Majority 2010.
Predicted Results
Figure 5: Predicted outcome of the 2012 Texas Congressional election using the proposed districts.
Predicted Results
Table 3: Predicted Republican Majority for the proposed 2012 districts*
District
Republican
District
Republican
District
Republican
Majority
Majority
Majority
1
366136
13
665562
25
1646.96
2
711703
14
1211050
26
724517
15
-48363.3
3
403353
27
1807.66
16
-49425.9
28
-183853
4
437238
29
-616473
5
562875
17
152679
18
-805659
30
-613687
6
884033
7
797404
19
239719
31
240049
20
-182077
8
363006
32
292401
9
-1143860
21
674302
33
157136
10
669904
22
711572
34
485696
35
-47759.7
11
273665
23
10075.7
12
282951
24
1224760
36
958037
*Zonal Statistics compiled from subtracting rasters. Negative values indicate Democratic Majority.
Actual Results
District
1
2
3
4
5
6
7
8
9
10
11
12
Table 4: Republican Majority for the 2012 districts
Republican
Republican
Majority
District
Majority
District
0.2499
13
0.5110
0.1805
14
0.0497
15
-0.1350
0.5616
16
-0.1825
0.2747
0.1751
17
0.4489
18
-0.2945
0.1055
0.1369
19
0.4773
20
-0.1709
0.3199
-0.3302
21
0.1413
0.1363
22
0.1801
0.3374
23
-0.0267
0.2484
24
0.1406
25
26
27
28
29
30
31
32
33
34
35
36
Republican
Majority
0.1179
0.2223
0.0985
-0.2141
-0.5055
-0.3360
0.1477
0.1057
-0.2625
-0.1441
-0.1793
0.2480
Actual Results
Figure 7: Actual Republican wins.
Actual Results
Figure 7: Actual Republican wins.
District
23
District
33
District
34
Figure 5: Predicted outcome of the 2012 Texas Congressional election using the
proposed districts.
Table 5: Results from Districts 23, 33, and 34
Francisco Canseco
Pete P. Gallego
Jeffrey C. Blunt
REP
DEM
LIB
87,547
Chuck Bradley
REP
96,676
Marc Veasey
DEM
5,841
30,252
Jessica Puente Bradshaw
REP
85,114
Filemon Vela
DEM
Steven Shanklin
LIB
52,448
89,606
2,724
LIB
Ed Scharf
GRN
2,105
Ed Lindsay
GRN
2,009
GRN
Conclusion
Goals
•Determine the percentage of voters in the current districts that are
registered Republican voters.
•Determine the Republican Majority in the new districts.
•Predict the number of new districts that will elect a Republican to the US
House of Representatives.
Objectives
•Demonstrate how redistricting is being used so that the party currently in
power in Texas can remain in power.
•Demonstrate how the distinction between redistricting and gerrymandering
are often difficult to determine.
•Determine if gerrymandering alone is enough to explain the results of the
2012 election.
•Demonstrate how decisions such as these made at the state level can
have repercussions on a national level.
Future studies should expand this analysis to include demographic
data on the population growth and distribution in said districts.
Questions?
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