Monday, February 3, 2020

Analysis of North Carolina State Senate Districts

In a previous post, I looked at the North Carolina State House of Representatives and the numbers within the new districts, based on a recent redistricting. This post looks at the numbers for the state senate and its districts, utilizing the classification approach and data. 

As a reminder: the classification approach that I take is based on a district's their partisan behavior, meaning the categories use a combination of factors: 

  • presidential results within the district; 
  • voter registration percentages (party registration and racial demographics) from the January 11, 2020 registration file from the North Carolina State Board of Elections; and,
  • the district's 'regionalism,' namely the percentage of registered voters in center cities (urban counties), outside of the center city but still inside an urban county, a surrounding suburban county, or a rural county.

As I showed in the previous post, the relationship between Donald Trump's 2016 vote performance in a district matches up very closely to the Republican candidate's vote performance in the 2018 election:



An adjusted r-squared value of 0.972 shows a very close relationship between the two percentages, so it should be expected that this close alignment (barring something dramatic happening this fall) should continue in terms of voter behavior.

Based on these factors and primarily the district's 2016 Trump vote performance, the following categories are created:


  • Safe Republican: voted over 55 percent for Trump in 2016
  • Lean Republican: between 50 and 54 percent for Trump in 2016
  • Competitive/Toss-Up: these are closest districts, usually 48-49 percent for either party's presidential candidate
  • Lean Democratic: between 50 and 54 percent for Clinton in 2016
  • Safe Democratic: over 55 percent for Clinton in 2016

Using this approach, the state senate districts fall into these categories:


  • Safe Republican: 21
  • Lean Republican: 6*
  • Competitive/Toss-Up: 4
  • Lean Democratic: 3
  • Safe Democratic: 16
First, a look at the presidential vote and the January 11, 2020 voter registration data by party registration in the various categories:


The first column represents the state numbers, with Donald Trump's 49.8 percent performance in 2016, and then the January 11, 2020 party registration of 36 percent registered Democratic, 33 percent unaffiliated, and 30 percent registered Republican. 

Within the 'safe' Republican districts, Trump received two-thirds of the vote in those districts, with an average of 40 percent of the registered voters being registered Republicans. These districts also have the lowest average registration of Democrats, at 28 percent. 

The 'Lean Republican" districts saw Trump's 2016 vote performance as an average 4 points above his state-wide performance, but with registered Democrats at an average of 41 percent; more on this aspect, and an important qualifier, when I look at 'regionalism' within the districts. 

Among the toss-up districts that are most competitive, Trump's performance is very slightly below his state performance, with party registration almost exactly at the state-wide percentages. 

Moving into the Democratic-advantaged districts, the lean Democratic districts are four points below Trump's performance, with a higher average Democratic voter registration and a lower Republican voter registration averages. In the Safe Democratic seats, Trump secured less than one-third of the vote, on average, with only twenty percent of the registered voters aligning with the Republican registration. 

Much of these differences can be explained by the racial and regional compositions of these districts; first, by voter race within the classifications: 


State-wide, the North Carolina voter pool continues to diversify in its racial composition, with barely two-thirds of the voters identifying as white, and one-third being persons of color. But in looking at the different categories, distinct differences emerge on their average racial compositions for the districts. 

For example, nearly 80 percent of safe Republican districts are white, with 21 percent being persons of color; conversely, 56 percent of safe Democratic districts are white and 43 percent are persons of color. An interesting division is between lean Republican and toss-up districts when it comes to average white voter percentages: 61 percent in lean Republican to 65 percent in toss-up. Again, the next factor of regionalism may help to explain this difference. 

Regionalism within the districts may be a key factor coming into this fall's campaign. As noted in the the previous blog post, I look at this factor in four distinct ways: 

  • the percentage of registered voters in center cities (urban counties);
  • those outside of the center city but still inside an urban county, and thus a suburban voter; 
  • the surrounding suburban county; and,
  • rural county.
The 2016 presidential results divided into these four categories show stark differences:


Hillary Clinton won central city precincts by a two-to-one advantage, while Donald Trump won surrounding suburban counties by the same spread. It was suburban precincts within urban counties that saw the true battleground, while rural counties went significant Republican, but not as Republican as their surrounding suburban counterparts. 

For the state senate districts, here are the regional breakdowns of the classified districts:


With the state being divided into 30 percent central city, a quarter in both suburban precincts in urban counties and surrounding suburban county, and barely 20 percent in rural counties, the distinctive composition of the various categories are reflected most notably in the safe districts: safe Republicans see an average of half of their precincts in surrounding suburban counties (the most Republican), while nearly two-thirds of safe Democratic districts are in central city precincts (the most Democratic). 

What may be critical to watch this fall are the suburban precincts inside urban counties that make up healthy percentages, on average, within the lean and toss-up districts: 31 percent within lean Republican (counterbalanced by a third of precincts in rural counties), 57 percent in toss-up, and 56 percent in lean Democratic districts. 


Like the NC State House analysis data, I created a Google spreadsheet that gives each senate districts' data compilation for folks to review and use. 


Again, these are not to be considered predictions, but rather what the past data tells us about the current districts' political behavior, and what that behavior may suggest. There is still a lot of time and fluidity between now and November, especially among voter registration and ultimately "who shows up to vote." But these analyses are intended to give a kind of baseline overview of the state legislative districts for considering later on this year. 

I'll update both analyses come the summer months with the latest registration data for the districts and the computations for the classifications. 

*Update: corrected the 'lean Republican' districts to 6 from 7 due to a typographical error.