Partisan gerrymandering produces political districts intentionally skewed in favor of one political party.
But it can also generate maps resistant to changing political sentiment — think red or blue waves.
We can test this too, by simulating what would happen if a particular party — in this case, the Democrats — did better and better.
Here's how that analysis looks for North Carolina's newly enacted state Senate district map.
We start with the unadjusted results of the 2020 presidential election, when Republicans won 50.7% of the popular vote in North Carolina.
If we distribute the 2020 vote share using the newly enacted Senate district map, Republicans would have won 31 seats and a supermajority in the NC House.
But if we distribute that 2020 vote share using the most common election outcome across all 100,000 maps generated by researchers, Republicans would have only won 29 seats and a simple majority in the House.
Now, watch how the map drawn by lawmakers compares to the maps generated by researchers when the vote share shifts.
In each simulation, we can increase the Democratic vote share little by little…
... again and again.
The map collection drawn by algorithms — which used "neutral" criteria like equal population and county and city boundaries — for the most part follows changing voting patterns.
The map drawn by state lawmakers? A little less so.
Watch how Republican map proposals can protect their power
By Tyler Dukes and
David Newcomb
Elections have consequences — at least they’re supposed to.
But a News & Observer analysis shows that, in addition to resulting in more seats for the GOP, the newly proposed maps for the two chambers of the N.C. General Assembly have a much better chance of preserving Republican majorities and supermajorities, even when the vote shifts toward Democrats.
The analysis compares maps drawn by lawmakers to a collection of tens of thousands of computer-generated maps that follow a set of more-or-less neutral redistricting criteria set by the legislature. By counting how many Republicans or Democrats are elected using each map and in past election, the findings show how often a given proposal lines up with the collection of maps.
But the N&O’s analysis also tested how resistant the map proposals are to changing political sentiment by simulating the outcomes if the Democratic vote percentage gradually increased.
The conclusion: it would take much larger than expected swings in voting patterns to wrest the legislative majority from Republican control.
Here’s how the analysis works — and what it shows for the state Senate.
Partisan gerrymandering produces political districts intentionally skewed in favor of one political party.
But it can also generate maps resistant to changing political sentiment — think red or blue waves.
We can test this too, by simulating what would happen if a particular party — in this case, the Democrats — did better and better.
Here's how that analysis looks for North Carolina's newly enacted state Senate district map.
We start with the unadjusted results of the 2020 presidential election, when Republicans won 50.7% of the popular vote in North Carolina.
If we distribute the 2020 vote share using the newly enacted Senate district map, Republicans would have won 31 seats and a supermajority in the NC House.
But if we distribute that 2020 vote share using the most common election outcome across all 100,000 maps generated by researchers, Republicans would have only won 29 seats and a simple majority in the House.
Now, watch how the map drawn by lawmakers compares to the maps generated by researchers when the vote share shifts.
In each simulation, we can increase the Democratic vote share little by little…
... again and again.
The map collection drawn by algorithms — which used "neutral" criteria like equal population and county and city boundaries — for the most part follows changing voting patterns.
The map drawn by state lawmakers? A little less so.
Tyler Dukes is the lead editor for AI innovation in journalism at McClatchy Media, where he leads a small team of journalists that helps the company’s 30 local newsrooms responsibly harness data, automation and artificial intelligence to elevate and strengthen their reporting. He was previously an investigative reporter at The News and Observer in Raleigh, N.C. In 2017, he completed a fellowship at the Nieman Foundation for Journalism at Harvard University. He is a graduate of North Carolina State University and grew up in Elizabeth City, N.C.
