The Atlas Of Redistricting

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The Atlas Of Redistricting

FiveThirtyEightSERIESThe Gerrymandering Project

PUBLISHED JAN. 24, 2018 AT 4:59 PM

By Aaron Bycoffe, Ella Koeze and David Wasserman

There’s a lot of complaining about gerrymandering, but what should districts look like? We went back to the drawing board and drew six different congressional maps for the entire country. Each map has a different goal: One is designed to encourage competitive elections, for example, and another to maximize the number of majority-minority districts. See how changes to district boundaries could radically alter the partisan and racial makeup of the U.S. House — without a single voter moving or switching parties. How we did this >>.[a]

GO TO: Nation Alabama Arizona Arkansas California Colorado Connecticut Florida Georgia Hawaii Idaho Illinois Indiana Iowa Kansas Kentucky Louisiana Maine Maryland Massachusetts Michigan Minnesota Mississippi Missouri Nebraska Nevada New Hampshire New Jersey New Mexico New York North Carolina Ohio Oklahoma Oregon Pennsylvania Rhode Island South Carolina Tennessee Texas Utah Virginia Washington West Virginia Wisconsin PARTISAN GOALS OTHER GOALS

Show current district boundaries

Gerrymander districts to favor Republicans

Gerrymander districts to favor Democrats

Match partisan breakdown of seats to electorate

Promote highly competitive elections

Maximize number of majority-minority districts

Make district shapes compact (using an algorithm)

Make districts compact while following county borders

← National map

Alabama’s current congressional district boundaries

How often we’d expect a party to win each of Alabama’s 7 seats over the long term — not specifically the 2018 midterms — based on historical patterns since 2006

100% D100% RBirminghamBirminghamMobileMobileHuntsvilleHuntsvilleMontgomeryMontgomery

USUALLY DEMOCRATIC DISTRICTS
HIGHLY COMPETITIVE DISTRICTS
USUALLY REPUBLICAN DISTRICTS

Current
1
0
6

Current
1
0
6

About the current map

These are the current congressional district boundaries, shaded by how likely each is to be represented by a party over the long term. This is not a forecast of the 2018 midterm elections.

The politics of Alabama’s maps

Party probabilities

Every district by the chance it will be represented by either party

DEM. CHANCES
GOP CHANCES

100%70%60%50%60%70%100%

Proportionally partisan

Majority minority

Democratic gerrymander

Highly competitive

Compact (borders)

Current

Republican gerrymander

Compact (algorithmic)

Expected seats by party[d]

The expected number of seats controlled by Democrats and Republicans, based on their long-term likelihood of winning each district

DEMOCRATSEVEN SPLITREPUBLICANS

1.95.1

1.95.1

1.95.1

1.65.4

1.15.9

1.06.0

1.06.0

0.76.3

Ranking Alabama’s maps

How the maps compare on district competitiveness, minority makeup, compactness, respect for local borders and the efficiency gap, an attempt to gauge how politically gerrymandered a set of districts is

Efficiency gapA measure of “wasted” votes, by the size of the advantage and which party it favors

Dem. gerrymander
D+4%

Majority minority
D+4%

Proportional
D+4%

Compact (borders)
D+6%

Competitive
D+6%

GOP gerrymander
R+10%

Current
R+10%

Compact (algorithmic)
R+17%

Competitive districtsNumber of districts in which both parties have at least a roughly 1-in-6 chance of winning

Compact (algorithmic)
2

Competitive
2

Compact (borders)
2

Current
0

Proportional
0

Majority minority
0

GOP gerrymander
0

Dem. gerrymander
0

Majority-nonwhite districtsNumber of districts in which a majority of the voting-age population is nonwhite

Proportional
2

Majority minority
2

Dem. gerrymander
2

Current
1

GOP gerrymander
1

Competitive
1

Compact (algorithmic)
0

Compact (borders)
0

County splitsNumber of times a map splits counties into different districts

Compact (borders)
5

Dem. gerrymander
8

GOP gerrymander
8

Majority minority
8

Proportional
8

Current
8

Competitive
12

Compact (algorithmic)
34

Compactness rankRank by the [e][f][g], from least (best) to greatest (worst)overall geographic compactness of its districts

Compact (borders)
1

Compact (algorithmic)
2

Dem. gerrymander
3

Majority minority
3

Proportional
3

Competitive
6

GOP gerrymander
7

Current
7

Breaking down Alabama’s current map by race

The racial makeup of each district, and each district’s likelihood of being represented by a member of a racial minority, based on election results since 2006.

WHITEAFRICAN AMERICANHISPANIC/LATINOASIAN/PACIFIC ISLANDEROTHER

SHARE OF POPULATION BY RACE
CHANCE OF BEING REPRESENTED BY A …

DISTRICT
MAJORITY RACE
0% 50% 100%
MINORITY MEMBER
DEMOCRAT
REPUBLICAN

1st

White

9%

>99%

2nd

White

10%

>99%

3rd

White

6%

>99%

4th

White

>99%

5th

White

3%

>99%

6th

White

1%

>99%

7th

African-American

95%
>99%

All demographic data from the 2010 census. Six of the seven alternative congressional district maps were drawn using Dave’s Redistricting App, a free online tool for experimenting with political boundaries. Its creator, Dave Bradlee, modified the app to make this project possible. The seventh map comes from software engineer Brian Olson, who wrote an algorithm to draw districts with a minimum average distance between each constituent and his or her district’s geographic center. Read more about how we drew these maps and how we are evaluating them in our methodology.[h]

Get the data on our GitHub page[i]

Additional contributions from Nate Silver and Julia Wolfe

Sources: Ryne Rohla/Decision Desk HQ, U.S. Census Bureau, Brian Olson

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