The National Agricultural Statistics Service of the United States Department of Agriculture presently uses labor-intensive aerial photographic interpretation to divide large geographical areas into manageable-sized units for estimating domestic crop and livestock production. Prototype software to automate the boundary delineation procedure, called the Computer-Assisted Stratification and Sampling (CASS) procedure, was developed by the National Aeronautics and Space Administration. The procedure uses image processing software on a Hewlett-Packard graphics workstation for the development of the operational approach.