This data set provides four feature classes. The base feature class is called BlockGroups_bg and isn't generalized. The weighted centroids feature class is called BlockGroups_bg_cent. The centroids are weighted by the U.S. Block Centroids population distribution. Use the weighted centroids in report aggregation and spatial overlay operations. The BlockGroups_bg and BlockGroups_bg_cent feature classes contain all the attributes. There are two generalized boundaries feature classes and called: BlockGroups_bg_gen2, and BlockGroups_bg_gen3. Use the generalized boundaries when creating study areas.