Redistricting Principles and Racial Representation

Abstract

How do traditional redistricting principles—contiguity, communities of interest, political subdivisions, incumbent protection, Section 5 of the Voting Rights Act, preservation of district core, and compactness—affect racial minority representation in congressional districts? Using data from the 2001-02 redistricting process, we find that compactness is the only principle that significantly affects minority representation, both in terms of majority-minority districts and minority influence districts, but these effects are contingent on the size of the minority community and extent of racial segregation in a state. Two other principles, Section 5 pre-clearance and protecting political subdivisions, improve minority representation in a more limited way. Thus, race-neutral redistricting criteria like the compactness principle, can dramatically affect the racial composition of the resulting districts and, thereby, affect minority representation.

Measuring the Compactness of Political Districting Plans

“…But calculating this number by brute force, enumerating the set of all feasible partitions and maximizing compactness over this set, is impossible. 7 Similar partitioning problems arise in applied mathematics (computer vision), computer science and operations research (the k-way equipartition problem), and computational biology (gene clustering), which have given rise to several important algorithms and candidate functionals. Unfortunately, none of these techniques are directly applicable to our districting problem as they are either designed for very small samples ( 100) or do not require partitions to be of even approximately equal cardinality.…”

“…In Davis v. Bandemer, 476 US 173 (1986)) Justices Powell and Stephens pointed to compactness as a major determinant of partisan gerrymandering, and Justices White, Brennan, Blackmun and Marshall cited it as a useful criterion. Nineteen state constitutions still contain a compactness requirement ( Barabas and Jerit, 2004). 4 An important argument against the use of compactness as a districting principle is that it may disadvantage certain population subgroups.…”

“… See Young (1988), however, and section 2.2 below 7. A back of the envelope calculation reveals that, for California alone, the cardinality of this set is larger than the number of atoms in the observable universe.…”

“…7 Without the constraint that each district have an equal number of voters the problem is the min-sum k-clustering problem which was shown bySahni and Gonzales (1976) to be NP-complete. An approximation for it in a general metric space which runs in n O(1=e) time has been found byBartal, Charikar and Raz (2001).…”

Redistricting California: An Evaluation of the Citizens Commission Final Plans

“…Maximizing either geographic compactness or nesting often hurts minority representation, and nesting can split city and county boundaries as well (Barabas and Jerit 2004;Cain and Mac Donald 2007). Yet aside from ranking the criteria in order of importance, Proposition 11 provided little guidance on how to resolve these conflicts, leaving the difficult task of reconciling them to the commission.…”