TX Senate

How gerrymandered are the maps coming out of the TXLege this session?

We report...you decide! See our table below for basic metrics and links to detailed analysis.

PLAN

Submitted By

MM
MM (%ile)
PB
 PB (%ile)
 Favors 2D (#of total)
Ensemble median
   2.14 50% 1  41.59% N/A  N/A
S2100 (Current map)
 
 1.33 39.28% 1  41.59% N  N/A
S2175
REP COLLIER (D) -10.17
0.01%
-5
0.39%
R 0 out of 617,270
S2174
REP ROMERO (D) -12.56
0%
-5
0.39%
R 0 out of 617,270
S2173
13-DIST FLOOR -13.86
0%
-3
3.34%
R 0 out of 617,270
S2172
Jeff Harper 2.94
61.7%
3
71.96%
D 168,753 out of 617,270
S2171
REP C TURNER (D) -10.17
0.01%
-5
0.39%
R 0 out of 617,270
S2168
S.B. 4 -12.17
0%
-7
0.02%
R 0 out of 617,270
S2167
SEN HUFFMAN (R) -12.19
0%
-7
0.02%
R 0 out of 617,270
S2166
SEN JOHNSON (D) -12.2
0%
-7
0.02%
R 0 out of 617,270
S2164
SEN ZAFFIRINI (D) -12.16
0%
-7
0.02%
R 0 out of 617,270
S2154
SEN LUCIO (D) -12.19
0%
-7
0.02%
R 0 out of 617,270
S2153
SEN HINOJOSA (D) -12.2
0%
-7
0.02%
R 0 out of 617,270
S2150
SEN JOHNSON (D) -12.2
0%
-7
0.02%
R 0 out of 617,270
S2149
SEN HUFFMAN (R) -12.2
0%
-7
0.02%
R 0 out of 617,270
S2148
SEN KOLKHORST (R) -12.19
0%
-7
0.02%
R 0 out of 617,270
S2146
SEN GUTIERREZ (D) -12.19
0%
-7
0.02%
R 0 out of 617,270
S2142
SEN MENENDEZ (D) 7.66
97.91%
3
71.96%
D 10,404 out of 617,270
S2141
SEN KOLKHORST (R) -12.19
0%
-7
0.02%
R 0 out of 617,270
S2139
SEN ZAFFIRINI (D) -12.16
0%
-7
0.02%
R 0 out of 617,270
S2137
SEN CREIGHTON (R) -10.13
0.01%
-7
0.02%
R 0 out of 617,270
S2135
SEN SELIGER (R) -12.19
0%
-7
0.02%
R 0 out of 617,270
S2134
SEN POWELL (D) -12.59
0%
-5
0.39%
R 0 out of 617,270
S2132
SEN POWELL (D) -10.2
0.01%
-5
0.39%
R 0 out of 617,270
S2130
C.S.S.B. 4 -12.19
0%
-7
0.02%
R 0 out of 617,270
S2129
SEN GUTIERREZ/ECKHARDT 1.6
42.73%
1
41.59%
N N/A
S2126
SEN HUFFMAN (R) -12.21
0%
-7
0.02%
R 0 out of 617,270
S2125
Ric Galvan -9.06
0.04%
-1
15.47%
R 250 out of 617,270
S2124
Alexander Morales -12.27
0%
-9
0%
R 0 out of 617,270
S2123
Statewide Senate 9.16
99.28%
9
99.81%
D 13 out of 617,270
S2122
SEN CREIGHTON (R) -11.63
0%
-7
0.02%
R 0 out of 617,270
S2121
SEN HUFFMAN (R) -12.21
0%
-7
0.02%
R 0 out of 617,270
S2120
SEN WEST (D) -12.2
0%
-7
0.02%
R 0 out of 617,270
S2119
SEN POWELL (D) -10.22
0.01%
-5
0.39%
R 0 out of 617,270
S2118
SEN CREIGHTON (R) -10.18
0.01%
-7
0.02%
R 0 out of 617,270
S2117
SEN GUTIERREZ (D) -12.21
0%
-7
0.02%
R 0 out of 617,270
S2113
SEN CREIGHTON (R) -11.62
0%
-7
0.02%
R 0 out of 617,270
S2112
SEN WEST (D) -12.19
0%
-7
0.02%
R 0 out of 617,270
S2109
SEN POWELL (D) -10.22
0.01%
-5
0.39%
R 0 out of 617,270
S2108
SEN HUFFMAN (R) -12.21
0%
-7
0.02%
R 0 out of 617,270
S2103
SEN WEST (D) -11.59
0%
-7
0.02%
R 0 out of 617,270
S2101
SEN HUFFMAN (R) -11.62
0%
-7
0.02%
R 0 out of 617,270

 

Metrics

MM = mean-median score (expressed as difference in vote share needed for majority)

MM (%ile) = percentile of MM score in ensemble

PB = partisan bias score (expressed as difference in seats won at 50% vote share)

PB (%ile) = percentile of PB score in ensemble.  

Favors = Does the map favor one party relative to another, compared with the ensemble? Possible values: D/R/N (neutral)/NA (not applicable)

2D (# of total) = number of ensemble plans that score worse on both MM and PB, or are equal on PB and worse on MM. We only assessed plans which favored one party over another on both PB and MM; e.g. in contrast S2100 favors Republicans slightly on MM, but is neutral on PB.

For integer-valued quantities such as partisan bias, the percentile value is sensitive to the exact definition. We used an average between the between the "weak" and "strict" definitions (i.e. "less than or equal to" and "strictly less than"), as implemented in the SciPy stats package (stats.percentileofscore(kind='mean') ).

Methodology

We generated an ensemble of 617,270 legal TX Senate plans using Markov Chain Monte Carlo algorithms as implemented in GerryChain (MGGG, 2018). Data was compiled from the Census Bureau (population data and geographic units) and the Texas Legislative Council (election returns from the 2020 Presidential and US Senate races).  Proposed plans were obtained from the Texas Legislative Council. Each plan was assessed on a variety of partisan metrics; the range of observed values in the ensemble is then used to assign a percentile value to each metric as computed for each proposed plan.