This release of ZIP Code Boundaries and Centroids incorporates ZIP+4 weighted centroids in the ZIP_Centroids layer, for ZIP Codes that have corresponding boundaries in the ZIP_Boundaries layer. For these ZIP Codes, the LAT and LON coordinates in the ZIP_Centroids layer are no longer calculated using the geographic center of the corresponding ZIP Code boundary. Instead, the updated process uses a weighted centroid based on ZIP+4 postal delivery locations. This ensures that the point locations in the centroids file are located in areas of concentrated postal delivery and helps reduce points located in remote areas of large ZIP codes, resulting in a more accurate and realistic location being associated with a ZIP Code. Steps are taken to ensure that revised centroid locations still fall within their respective ZIP Code boundaries.
Note: For customers who wish to continue to access geographic centroids of ZIP Codes, the LAT and LON coordinates in the ZIP_Boundaries layer will continue to contain geographic centroids calculated form the boundary, ideal for boundary labeling and map display.