This month’s map depicts the mean center of population (MCP) of Hampton Roads between 1970 and 2020. The mean center of population is the average location of the population within a defined area. Imagine balancing a rigid, flat map of Hampton Roads on a point but the map is weighed down by the number of people who live here and where they live. The location on the map where the map stays balanced is the mean center of population. How is this location useful for planners? By following the change in the center of population over time, we can summarize how and where the population has shifted around the region and perhaps make predictions about where the population will shift in the future.
In 1970, the MCP was in the Elizabeth River, near the eastern shore of Craney Island. There was a large shift in population to the east and slightly south between 1970 and 1990 as the population of Virginia Beach increased by 128% and Chesapeake by 70% (see the population chart in the map). By 1990, the MCP was adjacent to the Norfolk International Terminals. Since 1990, the center of population has been shifting gradually back toward the west, with a slight northward movement. The latest population count from 2020 places the MCP in the middle of the Elizabeth River, between Craney Island and the Norfolk International Terminals.
The largest shift in the center of population was between 1980 and 1990 where it moved 0.89 miles to the southeast. The shortest distance occurred between 2010 and 2020 with only 0.1 mi of movement to the northwest. The population growth in Virginia Beach slowed down after 1990 and appears to have had less of an effect on the MCP in later decades. Growth in western localities such as Chesapeake, Suffolk, and Isle of Wight along the Peninsula has pulled the mean center of population back toward the west and slightly northward.
Will the population continue to move toward the north and west? The HRPDC develops a socioeconomic forecast for each cycle of the HRTPO’s Long Range Transportation Plan (LRTP). This forecast of future population, along with other factors, helps regional planners identify future transportation needs. The population projections are captured in Traffic Analysis Zones (TAZ), which are based on census geography. The estimated MCPs for 2040 and 2045 were calculated based on the TAZs with the 2040 and 2045 socioeconomic forecast data. These population forecasts show a continuation of the trend of population shifting back toward the west and the north over the next two decades. The 2050 socioeconomic forecast is in development now and it will be interesting to see if the trend continues.
Historic census data at the tract level is available for Hampton Roads beginning in 1970, which coincides with when most of the counties and independent cities were in their current configuration (see the Historic County Boundaries of Hampton Roads StoryMap for more information). The MCPs for Hampton Roads were calculated using GIS for each decade beginning in 1970 with population counts from the decennial censuses. Census tracts were available for all localities in all years except for 1970 where the counties of Gloucester, Isle of Wight, Southampton, and Surry and the City of Franklin were not divided into tracts. The population for the entire county or city was used instead.
IPUMS NHGIS, University of Minnesota, https://www.nhgis.org (historic census data and geography); HRTPO, Hampton Roads 2009 and 2040 Socioeconomic Data by TAZ and Hampton Roads 2015 and 2045 Socioeconomic Data by TAZ.