South Atlantic Low-Urban Historic Landscapes

This cultural resource indicator is an index of sites on the National Register of Historic Places surrounded by limited urban development. It identifies significant historic places that remain connected to their context in the natural world. This indicator originates from the National Park Service and various state historic resource agencies.

Reason for Selection

Low-urban historic landscapes indicate significant cultural landscapes whose cultural context has been less impacted by urban growth. Cultural landscapes are “properties [that] represent the combined works of nature and of man” (UNESCO 2012). Reductions in natural habitat within these cultural landscapes reduce their overall historic and cultural value.

Input Data

• South Atlantic Blueprint 2021 extent
• Base Blueprint 2022 subregions
• 2019 National Land Cover Database (NLCD)

• National Register of Historic Places data from the National Park Service and various state historic resource agencies

  The National Register of Historic Places reflects what Americans value in their historic built environment. It is the collection of our human imprint on the landscape that records through time our changing relationship with the landscape, bridging between modern life and our history by providing, as closely as possible, experiences that evoke our empathy and understanding of previous eras.

  We combined the following data sources:

  • The National Register of Historic Places - all point layers from the NRIS_CR_Standards_Public geodatabase, including historic buildings, districts, objects, sites and structures (accessed 3/2021). We use this data only in Alabama and Georgia, where no improved state-specific layer is available
  • Some states maintain their own, improved versions of the National Register of Historic Places, while other states rely on the nationwide version maintained by the National Park Service. In Virginia, North Carolina, Florida, and South Carolina, we obtained the following state-specific point and polygon data for places on the National Register:
    • Virginia listed historic districts boundaries
    • Virginia listed site points
    • North Carolina local district boundaries
    • North Carolina NCHPO_NR_SL_DOE_Boundaries
    • North Carolina NCHPO points
    • Florida national register
    • South Carolina NRHP_Districts-Areas_Non-Restricted
    • SC_NRHP_Structures_points Non-Restricted

Mapping Steps

• Urban areas are defined using the following classes from the 2016 NLCD - Developed, High Intensity; Developed, Medium Intensity; Developed, Low Intensity; Developed, Open Space. Classify all urban pixels as 1 and all other pixels as 0.
• Calculate the percent urban in a 270 m radius circle for each pixel using focal statistics in ArcGIS. Since the NLCD data resolution is 30 m pixels, use 270 m (9 pixels) to approximate a 250 m radius. Retain all pixels that are < 50% urban within a 270 m radius.
• Create a historic places layer as follows:
  • The North Carolina NCHPO points file contains points for both state-level and national-level historic places. To make these data comparable with data from other states, remove the state-specific points using information from the attribute table (remove any point that has a blank value for the YearNR field).
  • Merge together the state-specific point layers (NC, SC, and VA) and the National Park Service-maintained National Register of Historic Places point layers (AL and GA) and buffer by 100 m.
  • Merge all polygon data and buffered point data into one layer and convert to a 30 m raster.
• Use the historic places raster to remove areas that fall outside of the historic places.
• Reclassify the above raster into 3 classes, seen in the final indicator values below.
• Clip to the spatial extent of the South Atlantic Blueprint.
• Clip to the ‘Atlantic Coastal Plain’, ‘Piedmont’, and ‘East Gulf Coastal Plain’ subregions. The source data also covers all states within those subregions. We didn’t include data in other subregions within those states due a combination of 1) lack of time to review new areas inside of those excluded subregions and 2) an oversight in which indicators were used for the Blueprint priorities in those subregions.

Note: For more details on the mapping steps, code used to create this layer is available in the Southeast Blueprint 2022 Data Download under BlueprintInputs > BaseBlueprint2022 > 6_Code.

Final Indicator Values

Indicator values are assigned as follows:

• 2 = Historic place with nearby low-urban buffer
• 1 = Historic place with nearby high-urban buffer
• 0 = Not in the National Register of Historic Places

Known Issues

• There are spatial mapping errors for some of the historic areas.
• Some historic areas with cultural importance are not necessarily captured in the National Register of Historic Places.
• The approach to measuring urban growth doesn’t capture degradation to historic places that were historically in larger cities (e.g., courthouses and other downtown buildings). It also doesn’t distinguish between historic places that have always been urban and historic places that used to be low-urban.
• This layer underrepresents some historic areas in Georgia and Alabama because we only used the point data from the National Register of Historic Places maintained by the National Park Service. We omit the polygon layers because they contain many GIS errors and often overestimate the extent of historic sites.
• While the indicator source data extends into other subregions in VA, NC, SC, GA, FL, and AL, those pixels are not included in the indicator because they were not used in the Blueprint priorities for that subregion. We didn’t include data in other subregions within those states due a combination of 1) lack of time to review new areas inside of those excluded subregions and 2) an oversight in which indicators were used for the Blueprint priorities in those subregions.

Disclaimer: Comparing with Older Indicator Versions

There are numerous problems with using Southeast Blueprint indicators for change analysis. Please consult Blueprint staff if you would like to do this (email hilary_morris@fws.gov).

Literature Cited

Homer, Collin G., Dewitz, Jon A., Jin, Suming, Xian, George, Costello, C., Danielson, Patrick, Gass, L., Funk, M., Wickham, J., Stehman, S., Auch, Roger F., Riitters, K. H., Conterminous United States land cover change patterns 2001–2016 from the 2016 National Land Cover Database: ISPRS Journal of Photogrammetry and Remote Sensing, v. 162, p. 184–199. [https://doi.org/10.1016/j.isprsjprs.2020.02.019].

Stutts M. 2014. National Register of Historic Places. National Register properties are located throughout the United States and their associated territories around the globe. [https://irma.nps.gov/DataStore/Reference/Profile/2210280].

UNESCO (2012) Operational Guidelines for the Implementation of the World Heritage Convention [1]. UNESCO World Heritage Centre. Paris. Page 14. [https://whc.unesco.org/archive/opguide12-en.pdf].