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Land Resource Units (LRUs) are defined by the National Soil Survey Handbook as aggregations of soil map units and subunits of Major Land Resource Areas (MLRAs). In the USDA NRCS Land Resource Hierarchy, LRUs are defined as the level between MLRAs and STATSGO and are mapped at 1:1 million scale. They also function as an important framework for the development of Ecological Site (ES) concepts. While the art and science of resource area mapping has advanced significantly in the past several decades, NRCS LRU regionalizations have typically lacked suitable scientific foundations in defining resource area concepts. With the recently adopted Provisional Ecological Site initiative (intended to complete initial inventory of ES in the contiguous U.S. by 2020), a pressing need has risen to stratify ES concepts by a practical and functional LRA. Because resource areas, such as Major Land Resource Areas (MLRA), are rarely discrete physical entities�?ooften being conceptualizations reflecting perceived biases from the mapper�?oit is important that resource areas implement rule-based procedures to test LRU concepts and geography. Here we present a methodology suitable for testing resource area boundary concepts and provide examples across the Continental U.S.