Looking at population change across NC’s census tracts

From 2010 to 2020, North Carolina’s population grew by 9.8% with 49 of our 100 counties increasing in population. Among the largest gains: Charlotte and its suburbs, the Triangle region, and areas from Jacksonville (Onslow County) to Wilmington along the Atlantic Ocean.

The map below shows a more detailed view of where we saw the biggest growth and losses amongst Census tracts. A Census tract is a unit of geographic measurement defined by the U.S. Census Bureau. Basically, it’s a way to break down counties into smaller geographic areas that the Census Bureau can measure how things (population, density) change over time.  Each tract generally has between 1,200 and 8,000 people in it – the optimal size is about 4,000. (You’ll notice that counties with smaller populations, like Tyrrell County, in the Northeast part of the state, are one Census tract; other counties, like Mecklenburg County, have many.) In the map below, blue represents that the Census tract increased in population from 2010 to 2020 and orange indicates that the tract decreased in population from 2010 to 2020.

In general, Census Tracts that experienced large population growth are located in counties that had the largest population growth

Eleven out of the 20 Census tracts with the largest population growth across the state in the past decade are in Mecklenburg County. Except for one tract in Onslow County, all Census tracts which tripled in population were located in either the Charlotte area or in the Triangle, often on the outskirts of the city centers.

Similarly, Census tracts that experienced large population losses are located in counties that had the largest population loss

Population loss was uneven across the state, but took place primarily in rural areas. We see the greatest losses in the I-95 corridor, from Robeson County to Northampton County.  In the Northeastern portion of the state, near the Virginia border, we see population loss in and southeast of Northampton County. In Northampton County, one of the counties with the largest population loss over the decade, areas further from the border to Virginia experience the largest losses.

Census tracts in Onslow County grew faster than those in nearby Brunswick County

We see something unique in the Southeast portion of the state: though Brunswick experienced some of the largest population growth among our counties, individual Census tracts in nearby Onslow County outpaced them. Interestingly, other Census tracts in Onslow also experienced some of the greatest population declines. In Onslow County, Census tracts in the city of Jacksonville experienced some of the largest population loss in the state whereas the populations in tracts outside of the city and close to the ocean experienced some of the largest population growth. The greater growth in two of the Census tracts in Onslow County, compared to the Census tracts in Brunswick County, might point to where there were more possibilities for expansion, e.g. in housing, although many factors contribute to population growth (births, deaths, and migration flows).

County level growth can obscure population change (positive or negative) in Census tracts

Many of the counties with large population growth or large population loss contain smaller areas that followed the patterns of the counties. The map below shows how population growth or loss is concentrated in certain areas, and, for instance, shows how a metropolitan area expands within more suburban counties.

Looking at population change in the smaller clusters within a county, however, also reveals where population growth or loss is located and how clusters within a county had opposite experiences in their population change between 2010 and 2020. Taking the example of Onslow County where the population growth and loss in Census tracts illustrate this contrast: the concentration of population loss in the city of Jacksonville and the population growth in areas around the city and closer to the Atlantic can show various stakeholders (e.g. city, county, and state governments, businessowners, residents) where investments need to be made and where it might be important to investigate the reasons behind, positive or negative, population change on a more granular level.

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Categories: Carolina Demographics, NC in Focus