Supplementary Report:

Racially Polarized Voting in Miami, Florida

Bryant J. Moy, PhD

July 1, 2023

Introduction and Scope of Work

My name is Bryant J. Moy, Ph.D., and I am a faculty fellow in the Center for Data Science and a Visiting

Assistant Professor in the Wilf Family Department of Politics at New York University. My qualifications

were further described in my initial report dated February 10, 2023.

I have been asked to analyze two proposed maps and provide my expert opinion on whether Black voters

could elect their preferred candidates in the newly constituted District 5. The first is Plaintiff’s 4 (“P4”)

and the second is the City of Miami’s proposed map (“City”). I was provided a geolocated voter file and

two shape files containing the geographic boundaries of newly constituted District 5.

In this report, I first provide racial demographic data of registered voters under the current map, the

P4 plan, and the city’s proposal. Second, I analyze the performance of the Black-preferred candidate in six

recent contests from 2022. Lastly, I re-analyze five contests from 2020 where I previously showed evidence

of racial polarization. I discuss how the newly proposed maps make it easier for Black voters to translate

their preferences to higher vote totals for their preferred candidate.

Summary of Findings

• Black voters in the City of Miami cohesively support a single candidate in the six recent elections:

Senate, Governor, County Judge Group 5, Chief Financial Officer, Commissioner of Agriculture, and

Attorney General. Moreover, non-Black voters’ support for the Black-preferred candidate is under 50%

in all contests. I find patterns of racially polarized voting in these contests.

• In the six recent elections, the Black-preferred candidate received the vast majority of the top twocandidate vote across both newly proposed districts. Moreover, the Black-preferred candidate would

have received more votes under the P4 plan than both the enjoined map and the city’s proposed plan.

• In the re-analysis of five previously polarized contests in 2020, I find that the Black-preferred candidate

would prevail under either of the proposed districts. More importantly, the Black-preferred candidates

under P4 have a marginally higher likelihood of prevailing given the larger makeup of the district

regardless of the Black share of the precinct.

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1 Racial Demographics of Registered Voters in District 5

There are 220,103 registered voters in Miami.1In Table 1 I show the racial composition of registered voters

under each map’s District 5. The City of Miami has a majority-Hispanic electorate with Anglos (non-Hispanic

whites) constituting 21% of the electorate and Blacks constituting 17% of the electorate.

Table 1: District 5 Racial Composition: Registered Voters

Race Enjoined Enjoined % P4 P4 % City City %

Anglo 6,813 14.0% 7,550 15.0% 6,782 14.0%

Black 28,054 57.6% 28,156 55.5% 27,793 57.0%

Hispanic 13,166 27.0% 14,324 28.0% 13,338 27.0%

AAPI/American Indian 661 1.3% 703 1.4% 713 1.5%

Total 48,694 - 50,733 - 48,626 -

2 Black-Preferred Candidates in Recent Elections

In this section, I analyze six recently help contests in 2022 to assess the extent to which they show patterns

of racially polarized voting: U.S. Senate, Governor, Attorney General, Chief Financial Officer, Commissioner

of Agriculture, and County Judge Group 5. I estimate the extent to which Black voters cohesively support

a single candidate using bivariate scatterplots. The x-axis corresponds with the Black Share of the Total

Citizen Voting Age Population for 2020, while the y-axis corresponds with the Black preferred candidate’s

vote share within Miami precincts.2I draw a linear line of best fit through the cluster of precincts. The

positive association means that as the Black share of the Citizen Voting Age Population increases, the

Black-preferred candidate receives a higher share of the vote.

For all contest, when the precinct is homogeneously Black, the identified Black-preferred candidate receives overwhelming support. Similarly, when precincts are homogeneously non-Black, the Black-preferred

candidate fails to receive the majority of the votes on average. All of the six contests analyzed show signs of

racially polarized voting.3

In Table 2, I indicate which individuals are the Black-preferred candidates and include their ethnicity in

parentheses: “B” represents Black, “W” represents non-Hispanic white, and “H” represents Hispanic of any

race.

Table 2: List of Elections Analyzed

Race Black-Preferred Candidate Non-Black-Preferred Candidate

US Senate Demings (B) Rubio (H)

Governor Crist (W) DeSantis (W)

Attorney General Ayala (B) Moody (W)

Chief Financial Officer Hattersley (W) Patronis (W)

Commissioner of Agriculture Blemur (B) Simpson (W)

County Judge Group 5 Seraphin (B) Diaz de la Portilla (H)

1. Consistent with the first report, I include Black, Anglo, Hispanic, AAPI/American Indian and exclude voters whose race

is recorded as “Other,” “Multi-racial,” or “Unknown” throughout the analysis. Registered voters recorded as both active and

inactive status are included in this analysis.

2. For this analysis, I use the top two candidates only.

3. In 5 of the 6 contest, when the Black share of CVAP is 0, the Black-preferred candidate receives a vote share in the low

40s. In the County Judge Group 5, however, when the Black share of CVAP is 0, the Black-preferred candidate receives 49% of

the vote. While still under 50%, there is suggestive evidence that the County Judge Group 5 may show less racial polarization

than the other contests.

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Figure 1: Black Preferred Candidates in Recent Contests

y = 0.416 + 0.63 x, R2 = 0.58

0.00

0.25

0.50

0.75

1.00

0.00 0.25 0.50 0.75 1.00

Black Share of CVAP

Demings Vote Share

Senate

y = 0.413 + 0.619 x, R2 = 0.60

0.00

0.25

0.50

0.75

1.00

0.00 0.25 0.50 0.75 1.00

Black Share of CVAP

Crist Vote Share

Governor

y = 0.436 + 0.575 x, R2 = 0.57

0.00

0.25

0.50

0.75

1.00

0.00 0.25 0.50 0.75 1.00

Black Share of CVAP

Ayala Vote Share

Attorney General

y = 0.419 + 0.615 x, R2 = 0.59

0.00

0.25

0.50

0.75

1.00

0.00 0.25 0.50 0.75 1.00

Black Share of CVAP

Hattersley Vote Share

CFO

y = 0.431 + 0.609 x, R2 = 0.58

0.00

0.25

0.50

0.75

1.00

0.00 0.25 0.50 0.75 1.00

Black Share of CVAP

Blemur Vote Share

Comm. of Agriculture

y = 0.491 + 0.431 x, R2 = 0.35

0.00

0.25

0.50

0.75

1.00

0.00 0.25 0.50 0.75 1.00

Black Share of CVAP

Seraphin Vote Share

County Judge Group 5

2.1 Performance of Black-Preferred Candidate in Recent Elections

Using precinct-level results of six elections held in 2022, I aggregate results to determine how many votes the

Black-preferred candidate would have received within the boundaries of the two newly constituted districts

(See Table 3). The two-candidate vote shares were similar across proposed districts.4 The Black-preferred

candidate would have prevailed in all contests analyzed at the district-level. According to Table 3, the

Black-preferred candidate would receive more votes under the P4 map than both the enjoined and the city’s

plan.

4. I use the top two candidate vote totals to examine the contest’s Black-preferred and non-Black-preferred candidates.

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Table 3: Black-Preferred Candidate Performance in Recent Election

Race Map Vote Total Black-Pref. # Black-Pref. % Non-Black-Pref. # Non-Black-Pref. %

County Judge Grp 5 Enjoined 7157 5234 73.1% 1923 26.9%

County Judge Grp 5 P4 7046 5433 77.1% 1613 22.9%

County Judge Grp 5 City 7548 5735 76.0% 1813 24.0%

US Senate Enjoined 16807 12230 72.8% 4577 27.2%

US Senate P4 15942 12718 79.8% 3224 20.2%

US Senate City 17753 13815 77.8% 3938 22.2%

Governor Enjoined 16849 11989 71.2% 4860 28.8%

Governor P4 15966 12462 78.1% 3504 21.9%

Governor City 17782 13530 76.1% 4252 23.9%

Attorney General Enjoined 16660 11979 71.9% 4681 28.1%

Attorney General P4 15876 12403 78.1% 3473 21.9%

Attorney General City 17678 13507 76.4% 4171 23.6%

CFO Enjoined 16554 11908 71.9% 4646 28.1%

CFO P4 15762 12418 78.8% 3344 21.2%

CFO City 17552 13477 76.8% 4075 23.2%

Comm. of Agriculture Enjoined 16607 12182 73.4% 4425 26.2%

Comm. of Agriculture P4 15830 12645 79.9% 3185 20.1%

Comm. of Agriculture City 17608 13743 78.0% 3865 22.0%

3 Black-Preferred Candidate Performance in Previously Racially

Polarized Elections

Table 4: Black-Preferred Candidate Performance in Previous RPV Elections

Race Map Vote # Black-Pref. # Black-Pref. % Non-Black-Pref. # Non-Black-Pref. %

President Enjoined 36848 28308 76.8% 8540 23.2%

President P4 38379 31312 81.6% 7067 18.4%

President City 41234 33233 80.6% 8001 19.4%

County Mayor Enjoined 32852 24968 76.0% 7884 24.0%

County Mayor P4 34145 27473 80.5% 6672 19.5%

County Mayor City 36703 29209 79.6% 7494 20.4%

County Judge Grp 9 Enjoined 12043 7281 60.5% 4762 39.5%

County Judge Grp 9 P4 12798 8198 64.1% 4600 35.9%

County Judge Grp 9 City 13325 8443 63.4% 4882 36.6%

Circuit Judge Group 57 Enjoined 12348 7563 61.2% 4785 38.8%

Circuit Judge Group 57 P4 13140 8741 66.5% 4399 33.5%

Circuit Judge Group 57 City 13685 8976 65.6% 4709 34.4%

Circuit Judge Group 67 Enjoined 12189 6362 52.2% 5827 47.8%

Circuit Judge Group 67 P4 12891 7219 56.0% 5672 44.0%

Circuit Judge Group 67 City 13428 7504 55.9% 5924 44.1%

In this section, I re-analyze five 2020 contests that exhibited signs of racial polarization in my previous

report: President, County Mayor, County Judge Group 9, Circuit Judge Group 57, and Circuit Judge Group

67. In Table 4, I aggregate the official election results for each district and show how many votes the Blackpreferred candidate would have received under each map. Across all contests, the Black-preferred candidate

would have received the majority of the votes in District 5.

Figures 2 - 6 depicts the relationship between the Black share of the Citizen Voting Age Population and

the share that the Black-preferred candidate received. I report the linear line of best fit and the R2in each

graph. As we see in the figures, Black voters are able to translate their preferences into high vote shares

for their preferred candidate. Furthermore, the P4 plan increases the likelihood that the Black-preferred

candidate will prevail over the enjoined map and the plan proposed by the city. Specifically, as shown in the

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equation, the intercept is shifted upward which meaning that the Black-preferred candidate is in a better

position to prevail given the larger makeup of the district regardless of the Black share of the precinct. Take

the County Mayor contest for example. The y-intercept shifts from .648 in enjoined map to .716 to the

plaintiff’s plan. This shift is even larger compared with the city’s plan (.638 to .716).

Figure 2: Presidential Election

y = 0.699 + 0.248 x, R2 = 0.79

0.00

0.25

0.50

0.75

1.00

0.00 0.25 0.50 0.75 1.00

Black Share of CVAP

Black−Pref. Candidate

P4

y = 0.629 + 0.345 x, R2 = 0.42

0.00

0.25

0.50

0.75

1.00

0.00 0.25 0.50 0.75 1.00

Black Share of CVAP

Black−Pref. Candidate

City

y = 0.628 + 0.353 x, R2 = 0.74

0.00

0.25

0.50

0.75

1.00

0.00 0.25 0.50 0.75 1.00

Black Share of CVAP

Black−Pref. Candidate

Enjoined

5

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Figure 3: County Mayor

y = 0.716 + 0.178 x, R2 = 0.66

0.00

0.25

0.50

0.75

1.00

0.00 0.25 0.50 0.75 1.00

Black Share of CVAP

Black−Pref. Candidate

P4

y = 0.638 + 0.288 x, R2 = 0.32

0.00

0.25

0.50

0.75

1.00

0.00 0.25 0.50 0.75 1.00

Black Share of CVAP

Black−Pref. Candidate

City

y = 0.648 + 0.288 x, R2 = 0.67

0.00

0.25

0.50

0.75

1.00

0.00 0.25 0.50 0.75 1.00

Black Share of CVAP

Black−Pref. Candidate

Enjoined

6

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Figure 4: County Judge Group 9

y = 0.478 + 0.325 x, R2 = 0.73

0.00

0.25

0.50

0.75

1.00

0.00 0.25 0.50 0.75 1.00

Black Share of CVAP

Black−Pref. Candidate

P4

y = 0.477 + 0.328 x, R2 = 0.73

0.00

0.25

0.50

0.75

1.00

0.00 0.25 0.50 0.75 1.00

Black Share of CVAP

Black−Pref. Candidate

City

y = 0.457 + 0.309 x, R2 = 0.46

0.00

0.25

0.50

0.75

1.00

0.00 0.25 0.50 0.75 1.00

Black Share of CVAP

Black−Pref. Candidate

Enjoined

7

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Figure 5: Circuit Judge Group 57

y = 0.547 + 0.227 x, R2 = 0.60

0.00

0.25

0.50

0.75

1.00

0.00 0.25 0.50 0.75 1.00

Black Share of CVAP

Black−Pref. Candidate

P4

y = 0.506 + 0.287 x, R2 = 0.64

0.00

0.25

0.50

0.75

1.00

0.00 0.25 0.50 0.75 1.00

Black Share of CVAP

Black−Pref. Candidate

City

y = 0.471 + 0.31 x, R2 = 0.55

0.00

0.25

0.50

0.75

1.00

0.00 0.25 0.50 0.75 1.00

Black Share of CVAP

Black−Pref. Candidate

Enjoined

8

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Figure 6: Circuit Judge 67

y = 0.427 + 0.273 x, R2 = 0.67

0.00

0.25

0.50

0.75

1.00

0.00 0.25 0.50 0.75 1.00

Black Share of CVAP

Black−Pref. Candidate

P4

y = 0.438 + 0.26 x, R2 = 0.61

0.00

0.25

0.50

0.75

1.00

0.00 0.25 0.50 0.75 1.00

Black Share of CVAP

Black−Pref. Candidate

City

y = 0.418 + 0.237 x, R2 = 0.33

0.00

0.25

0.50

0.75

1.00

0.00 0.25 0.50 0.75 1.00

Black Share of CVAP

Black−Pref. Candidate

Enjoined

9

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Summary

In this report, I analyzed two newly proposed maps for District 5: plaintiff’s 4 (“P4”) and the city’s plan

(“City”). I analyzed six recent elections and found that Black support is cohesive for a single candidate

and non-Black support for the Black-preferred candidate is under 50%. Moreover, in those elections, the

Black-preferred candidate will receive the majority of the votes in the newly proposed districts. Next, I reanalyzed five contests that previously showed evidence of racial polarization. The Black-preferred candidate

would prevail in either of the two proposed districts. More importantly, Black voters would have seen their

preferred candidate receive a higher vote share under P4 than both the city’s plan and the enjoined plan.

Bryant J. Moy, Ph.D.

Date: July 1, 2023

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