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Description:

The Five-Digit ZIP (Zoning Improvement Plan) Code boundary layer (zip5) is derived from the Geographic Data Technology (GDT), Inc. ZIP Boundary and Inventory Files (v. 5.0) and stored in the EPA Spatial Data Library System (ESDLS). This layer contains data for the conterminous U.S. and is divided into state directories that are contained in a ARC/INFO spatial data library in ESDLS. A ZIP code is a number of up to nine digits used by the U.S. Postal service to identify an area where mail is delivered. The zip5 boundary layer shows the boundaries for five-digit ZIP code delivery areas. The first digit of five-digit zip code divides the country into 10 large groups. Within these areas each state is divided into 10 smaller areas that are identified by the second and third digits. The fourth and fifth digits identify a post office, station, branch or local delivery area. This data layer provides a valuable source for applications that include base mapping as well as applications that incorporate spatial analysis functions using ZIP codes.

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Record Details:

Record Type:DATA SET

Product Published Date:01/01/1997

Record Last Revised:12/10/2002

Record ID: 6065

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Quality Assurance:

Title :FIVE-DIGIT ZIP CODE BOUNDARIES FOR THE CONTERMINOUS UNITED STATES

Data Use & Constraints :Several checks were made against the processed data to ensure the data were correctly processed and inserted into ESDLS. These checks included unit testing, peer reviews, and testing by Product Assurance (PA). The (PA) team performed several checks on the data to ensure accuracy. The following list illustrates the steps taken: 1. Execute an Arc Macro Language (AML) routine that checks for the existence of the ZIP code data layer for each state; and that the data layer was spatially inside the boundary for its respective state. 2. Check for correct projection parameters and data fields. 3. Perform visual verification of the data using ArcView. These verifications include checking ZIP code boundaries against the Postal Service database on the World Wide Web for random areas in the conterminous U.S. Use Constraints: This is a licensed product from Geographic Data Technology, Inc.