By Lynn Teague
Brad drew my attention to an article in The Washington Post about mathematics and
redistricting. This brought to mind some important math about South Carolina’s current
legislative districts. The majority of South Carolina’s legislative districts are non-competitive in
the general election. The winning candidate is selected in the primary in June. This makes
November elections meaningless in many cases and encourages polarization, since highly
engaged and often extreme voters are especially likely to participate in primaries. It also seems
odd, since we know that in S.C. statewide races the majority party draws about 55% of the vote,
while they now control a super-majority in the Senate and House. The most common
explanation for this disparity in proportions is partisan gerrymandering.
However, you can’t fix a problem if you don’t know what the problem really is, and guessing
isn’t good enough. Even well-designed districts can look odd, and gerrymandered districts can
look okay. An eyeball test isn’t enough. So, League of Women Voters of South Carolina board
member Matthew Saltzman supervised a Clemson grad student thesis to evaluate whether our
districts meet mathematical tests of partisan gerrymandering. Anna Marie Vagnozzi used a test
originally employed in the 2017 case League of Women Voters v. Commonwealth of Pennsylvania. Vagnozzi generated millions of maps and found that the current S.C. maps do not fall at the extremes of the resulting distribution and do not seem to have been pushed to extremes by partisan bias. Instead, they fall very much where the presumably fair post-litigation Pennsylvania maps do.
So, why are South Carolina’s maps so non-competitive? Some of this arises from demography.
South Carolina retains a significant level of racial polarization in voting, so the tendency of black
voting-age populations to be concentrated in some areas, especially urban centers, is a major factor. Votes are wasted when a group of voters are clustered together in such high numbers that their district would have been won by the same party without many of them. White populations are more evenly distributed throughout the state and this provides an automatic electoral advantage, giving them greater voting strength with fewer votes wasted.
The other big factor is incumbent protection. Incumbents of both parties have engineered their
districts to be “safe.” They have amplified the differences caused by demography to create even
more extreme differences by carefully choosing their boundaries to include neighborhoods favorable to them and exclude others. This bipartisan process, repeated through successive redistricting cycles, has led to some excessively predictable districts. (Bipartisanship is not always the Holy Grail of good politics.)
A very recent presentation on redistricting in South Carolina is posted on-line at the League website. It includes maps of our noncompetitive districts as well as a short summary of Vagnozzi’s research and discussion of where we are in the redistricting process.
Lynn Teague is a retired archaeologist who works hard every day in public service. She is the legislative lobbyist for the South Carolina League of Women Voters.