There are 36,104 unique census block codes that have no population and which were not able to be conflated to match the Precisely database. For a list of these blocks, refer to the ExcludedBlocks tab in the census_boundaries_statistics.xlsx workbook, found in the documentation folder of the product delivery file.
Due to changes to shorelines over time, some census features that are part of shoreline areas may be deleted during the shoreline clipping process. This results in a small number of census features being available only in the non-shorelined (*_b) layers.