Description: U.S. ZIP Codes provide detailed boundaries that are consistent with the tract and county datasets and are effective at the national level. This dataset provides four feature classes. The base feature class is called ZIPCodes_zp. The centroids feature class is called ZIPCodes_zp_cent. The ZIPCodes_zp and ZIPCodes_zp_cent feature classes contain all the attributes. There are two generalized boundary feature classes and called: ZIPCodes_zp_gen2 and ZIPCodes_zp_gen3. Use the generalized boundaries when creating study areas.