By on 8.3.21 in Census 2020, Elections & Voting, NC in Focus

This is the third post in a three-part series previewing redistricting in North Carolina. Earlier posts provide an overview of redistricting and a preview of what redistricting means for NC’s House.

Typically, redistricting starts in April, but the data delays because of Covid-19 pushed back the redistricting data release to August. Redistricting data from the 2020 census will be released on Aug. 12 at 1 p.m. ET. The redistricting files are expected to be uploaded to the Census Bureau’s FTP site.

When that happens, North Carolina legislators will begin the process of redrawing the state’s 14 Congressional districts, 50 state senate districts, and 120 state house districts.

In North Carolina, the redistricting process for the General Assembly is now partially determined by an algorithm that helps to ensure that districts align with county boundaries as much as possible. During the early summer of 2021, we worked with a team of researchers from across the state to understand the potential impacts of population change on state-level redistricting. (Learn more about the team and our approach.) In this post, we break down what might happen in North Carolina’s Senate.

Remember! The data presented here are based on estimates of population change over the decade based on trends in births, deaths, and migration. These estimates have a margin of error and are not the same as the 2020 Census. We are using this data to give us insights into what we might expect when the first local Census results are released in mid-August.

Key takeaways:

  • The ideal district size for NC Senate seats will be 208,788 and can range between 198,348 and 219,227.
  • Cabarrus, Johnston, and Onslow counties could become single county districts.
  • County clusters have the greatest volatility in the northeast and in the region just west of Mecklenburg (Gaston/Lincoln to Buncombe/Henderson).
  • The 2020 Census numbers will be different than the estimates presented here; these differences, even if small, could have a large impact on the political map.

How many seats are in North Carolina’s Senate?

There are 50 seats in North Carolina’s Senate.

What is the “ideal district size”?

The ideal district size is equal to the state’s resident population (10,439,388) divided by 50 or 208,788. During the redistricting process, the population of a district can range within 5% of this ideal size, meaning districts can range from 198,348 to 219,227.

What are potential changes/implications?

We evaluated the legislative county clusters identified under the 2010 Census and under four sets of estimates for the 2020 population of each county (full methodology). In total, the four sets of estimates produced 69 potential county cluster maps.

Which counties may be gaining seats or representation?

Estimates of growth over the decade suggest the following counties could gain representation in the NC Senate after the release of the 2020 Census:

  • Wake shifts from Wake-Franklin (5 districts) to either:
    • Wake (5)
    • Durham-Wake (7)
  • Cabarrus, Johnston, and Onslow could each become a single seat

Which new clusters are likely to emerge in the 2020 redistricting process?

There were three county clusters that are not in the current NC House map but emerged in all four of the estimates evaluated:

  • Guilford-Rockingham (3 districts)
  • Cabarrus (1)
  • Johnston (1)
  • Beaufort-Craven-Lenoir (1)
  • Davidson-Davie (1)
  • Wayne-Wilson (1)
  • Durham-Person (4)
  • Haywood-Madison (1)

These changes would have implications for counties that previously were previously clustered with the counties listed above. For example, a Guilford-Rockingham cluster would impact Alamance and Randolph counties, which were previously clustered with Guilford.

Which county clusters may be unchanged in the 2020 redistricting process?

There were two county clusters that are in the current map (based on 2010 Census) and were also present in all four estimates models. These are the single district clusters of Rowan-Stanly and Greene-Pitt. If these clusters remain in the clusters identified with the 2020 Census data, these districts will be unchanged.

Where is the greatest uncertainty?

There is a lot of volatility in the clusters produced across the different population estimates that we evaluated as we tried to understand what to expect with the release of the 2020 Census. Notably, in the NC Senate map, the instability was mostly in the northeast/Outer Banks and from west of Mecklenburg to Buncombe/Henderson. For example, the image below highlights the three potential county clusters west of Mecklenburg and four potential clusters in the northeast identified using 2020 population data from the Redistricting Data Hub.


What do we not know?

While these data can help us understand what we might expect when the 2020 Census data is released in the next few weeks, we are still waiting for the official Census numbers. These should be released by August 16, 2021.

This process can be confusing. Even once we have the Census numbers, there may be multiple county clusterings that are identified, meaning that there will be decisions about which counties should be clustered together for the purposes of redistricting. Once the county clusters have been selected, the redistricting process fully begins, as there are often multiple districts within the county clusters. In these instances, there are many potential ways to draw the corresponding lines, and there is less explicit guidance than what exists for identifying potential clusters.

How can I learn more?

We will be writing a series of posts and explainers about redistricting in the coming days and will disseminate additional information through our newsletter. You can sign up on the top right-hand side of this page.

If you have questions about redistricting, let us know and we will do our best to answer.

August 5: The Census Bureau is holding an informational webinar in advance of the redistricting data release on Thursday, August 5 at 1 p.m. EDT.

August 11: The NC Office of State Budget and Management is hosting a virtual event to discuss how and where to get the data and the legal foundation of redistricting.

Additional analysis and commentary can be found at:


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