Expansive soils have been documented in the Las Vegas Valley for many years; however, the extent of these soils horizontally and vertically was relatively unknown. This study investigates the extent and expansivity of soils in the Las Vegas Valley. It is an attempt to present an empirical model predicting areas where expansive soils may be encountered. A correlation between swell test results and plasticity index was evaluated for two datasets, and results compare favorably with relationships established for other areas. Analyses were conducted to evaluate correlations between expansion potential and topographic slope, soil classification, and locations of subsidence-related faults and earth fissures. Results show that expansion potential generally increases with decreasing slope, finer grain-size and increasing plasticity. Over ninety-four percent by length of mapped subsidence-related faults are located within areas having some expansion potential. Eighty-eight percent of earth fissures are found in areas exhibiting moderate to critical expansion
