A mathematical model for political districting with compactness consideration and an application to Kentucky Senate districting

Patrick, Kevin T.

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https://hdl.handle.net/2142/16747 Copy

Description

Title

A mathematical model for political districting with compactness consideration and an application to Kentucky Senate districting

Author(s)

Patrick, Kevin T.

Issue Date

2010-08-20T17:56:39Z

Director of Research (if dissertation) or Advisor (if thesis)

Önal, Hayri

Department of Study

Agr & Consumer Economics

Discipline

Agr & Consumer Economics

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Political Districting
• P-Center Formulation
• Compactness
• Kentucky Senate

Abstract

The basic redistricting problem is defined as aggregating a set of base (indivisible) units into contiguous geographical areas with almost equal voter population, called districts, and districts into a district plan. The method used to create districts can have a substantial impact on election results and therefore the laws passed. Districting is a very difficult problem that usually leads to severe political debate no matter who does it and what the result looks like. The problem becomes even more convoluted when the very people that can benefit most from generating district plans are given control. Traditionally this problem is solved by map-making skills based on subjective criteria (typically partisan interests). In addition to the two basic criteria, namely contiguity and population equality, other spatial and socioeconomic criteria have been considered when generating district maps. These additional criteria may involve compactness, community integrity, racial concerns, etc. Generating district maps by simultaneous consideration of various criteria leads to a challenging combinatorial problem; therefore, sophisticated methods are needed for this purpose. Development in computer technologies in recent decades made it possible to draw district boundaries using computer software although this approach has not been adopted in most states. This thesis introduces a mathematical programming model, specifically a linear mixed-integer program, to create a politically unbiased districting plan that can be augmented to meet the needs of the user. This method is empirically tested in an attempt to create a state Senate district plan for Kentucky. Kentucky was chosen in particular because of a Supreme Court case that eventually held that the proposed districting plan violated the State Constitution and a new plan needed to be created that contained compact and contiguous districts each consisting of a population within 5% of the ideal all the while dividing counties as rarely as possible. In addition, both the number of senate districts and base units in the State of Kentucky are relatively small, making the state a good choice for model testing. The thesis concludes with an assessment of the relationship between compactness and the demographic composition of the district maps generated by the model vis-à-vis the actual state Senate district map.

Graduation Semester

2010-08

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http://hdl.handle.net/2142/16747

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Copyright Kevin T. Patrick

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