The Gerrymander How to Divide and Conquer your Enemy

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The GerrymanderHow to Divide and Conquer your
Enemy

• A Case Study on Map Use Abuse

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Gerrymander Origin

• Gerrymander, or Gerrymandering, is derived from
  Gerry Salamander
• Elbridge Gerry was the governor of Massachusetts
  before becoming Vice President under James
  Madison.
• The misshapen district which was drawn and passed
  through the Massachusetts legislature in 1812 by
  the Democratic Republicans.
• The district resembles a salamander.
• This is a form of redistricting in which
  electoral districts are manipulated for an
  electoral advantage for one political party.
• This careful shaping of the voting district gave
  them and advantage over there Federalist party
  rivals.

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Gerrymander Origin

• Elbridge Gerry, the 5th Vice President of the
  United States. In office from March 4, 1813, to
  November 23, 1814, under President James Madison

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• This satirical cartoon depicting a district in
  Essex County, Massachusetts, as a dragon, was
  printed in the Boston Gazette, March 26, 1812.
  The electoral districts were drawn by
  Democratic-Republican members of the
  Massachusetts legislature to favor their
  incumbent party candidates. Governor Elbridge
  Gerry signed the redistricting into law, although
  reluctantly.

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Gerrymander Origin

• Redistricting by gerrymandering is typically used
  by those of a political party in power, or the
  incumbents.
• This redistricting will then advantage their own
  party, or disadvantage the opposing party, or
  members of a racial, national, linguistic,
  religious, or class group.
• Redistricting can especially favor a particular
  political party in single-winner electoral
  systems that elect representatives to represent
  voting districts.
• Such systems, are called first past the post, or
  winner takes all.
• Typically, such voting systems favor few
  political parties, e.g., our democratic and
  republican parties.

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Example of Positive Effects of Gerrymandering

• In Arizona, the Hopi native American tribe is
  surrounded by the historically rival Navaho
  tribe.
• In this case there is good cause to elect
  different representatives to the two tribes that
  are geographically interlocked.
• Another, more contentious case, is a narrow
  California congressional district along the coast
  separate from the inland district.
• The two districts have different concerns that do
  not always overlap.

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Gerrymandering Techniques

• Two gerrymandering techniques, packing and
  cracking, allow maximizing votes for one party
  while minimizing votes for the opposition.
• Packing concentrates opposition voters in a few
  districts that are already a majority in that
  party.
• Cracking breaks down regions that will dilute the
  opposition so that a slight majority for the
  other party.

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Gerrymandering Example Diagram
Left Four districts of even Red and Green
party voters, 8 from each party. Right
Redrawing the balanced electoral districts in
this example creates only one packed district of
14 green voters. The remaining 18 green voters
are cracked across the 3 other districts. The
result is a 3-to-1 advantage for the Red party.
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Gerrymandering Effects

• The effects of gerrymandering can be detrimental
  to the democratic process
• Gerrymandered districts favor incumbents that are
  difficult to unseat in elections, thus creating
  safe seats.
• Safe districts with incumbents with less
  incentive to govern by constituents needs
• Proportional or descriptive representation is
  then altered
• Meaningful campaigns are also influenced, further
  demoralizing voters.
• In the 2002 election, only four incumbents in the
  US Congress were defeated, the lowest number in
  history.
• This was in part due to redistricting and
  gerrymandering by incumbents.

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Gerrymandering Example Arizona's 2nd
congressional district

• The unusual division was not drawn to favor
  politicians, but to separate the Hopi and the
  Navajo tribes, due to historic tensions.

• Since the Hopi reservation is completely
  surrounded by the Navajo reservation, and in
  order to comply with current Arizona
  redistricting laws, some means of connection was
  required that avoided including large portions of
  Navajo land, hence the narrow Colorado River
  connection.

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Gerrymandering Example Texass 22nd
congressional district

• This district was the result of redistricting in
  2003, when Texas congress had become republican,
  the first time since Reconstruction

• This mid-decade redistricting resulted in six
  additional seats in US congress

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Gerrymandering Example Californias 38th
congressional district

• District 38 was produced by California's
  incumbent gerrymandering, as home to democrat
  Grace Flores Napolitano, who ran unopposed in
  2004

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Gerrymandering Example Illinoiss 4th
congressional district

• The unusual "earmuff" shape connects two Hispanic
  neighborhoods while remaining contiguous by
  following Interstate 294.

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Gerrymandering Example Texass 25th
congressional district

• U.S. congressional districts covering Travis
  County (outlined in red) in 2002, left, and 2004,
  right.
• In 2003, Republicans in the Texas legislature
  redistricted the state, diluting the voting power
  of the heavily Democratic county by parceling its
  residents out to more Republican districts.
• The district in orange is the infamous "Fajita
  strip" district 25 (intended as a Democratic
  district), while the other two districts (10 and
  21) are intended to elect Republicans.
• District 25 has now been redrawn as a result of
  the 2006 U.S. Supreme Court decision, and is no
  longer a "Fajita strip."

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Gerrymandering Example Texass 25th
congressional district

• U

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Gerrymandering Example Texass 25th
congressional district

• The conservative 51st District was renumbered the
  50th District after the 2000 census, and was
  gerrymandered to include the more conservative
  community of Clairemont Mesa, and to exclude the
  relatively liberal areas of La Jolla and Univ. of
  Calif. at San Diego, which were moved to the
  more-liberal 53rd District.

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Remedies

• Redistricting was only allowed after the ten year
  census
• The United States Supreme Court upheld all of the
  2003 Texas redistricting engineered by former
  House Majority Leader Tom DeLay, except for the
  "fajita" district, which would have affected
  racial and ethnic minority groups.
• This decision now allows politicians to redraw
  and gerrymander districts as often as they like
  to protect their political parties and seats,
  provided they do not harm racial and ethnic
  minority groups.

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Remedies

• Some states have taken or considered taking steps
  to revoke this rule
• A separate non-partisan redistricting authority
  would choose districts in order to prevent abuse.
  
• Some examples are
• Washington State Redistricting Commission
• Arizona Independent Redistricting Commission
• Rhode Island Reapportionment Commission
• New Jersey Redistricting Commission
• The city of San Diego also uses such a system
  according to its municipal charter.

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Shape Constraints

• A GIS remedy is consider the shape of a district
  as a limiting factor.
• One way to define shape is to compare a parcels
  perimeter length to its area.
• This is
• This value is dimensionless
• The value for a circle is 1
• The value for a square is 1.1284
• The value for a rectangle five times longer than
  its end is 1.5139
• Limiting this number below a certain value would
  also limit gerrymandering.

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References

• Elbridge Gerry, Wikipedia, http//en.wikipedia.org
  /wiki/Elbridge_Gerry
• California's 50th congressional district,
  Wikipedia, http//en.wikipedia.org/wiki/United_Sta
  tes_House_of_Representatives,_California_District_
  50
• Politics of Texas, Wikipedia, http//en.wikipedia.
  org/wiki/Politics_of_TexasRedistricting_Disputes_
  and_the_1990s
• Salamander, Wikipedia, http//en.wikipedia.org/wik
  i/ImageSalamandra_salamandra_28Marek_Szczepanek
  29.jpg
• Longley, Paul A., Goodchild, Michael F., Maguire,
  David J., Rhind, David W., Geographic Information
  Systems and Science, Publisher Wiley