Soybean germplasm has been identified that exhibits a slow-wilting phenotype at the onset of drought. Unfortunately, the slow-wilting trait has yet to be exploited for cultivar improvement because the empirical yield responses have been variable across years and locations. This simulation study was undertaken to assess the probabilities across the soybean production areas in the U.S. for improvement in crop water use efficiency and yield by incorporating the slow-wilting trait into commercial varieties. Experimentally, the slow-wilting response has now been shown to be associated with a maximum transpiration rate by the plant that is reached at an atmospheric vapor pressure deficit of about 2.0 kPa and above. Limitation of transpiration at high vapor pressure deficit results in increased overall water use efficiency, soil water conservation, and sustained physiological activity late in the season under drought conditions. A relatively simple, robust mechanistic soybean model was used to simulate soil water balance and soybean yield in approximately 8,000 locations using about 50 years of historical weather records across the production areas in the U.S. The results of these simulations provide a geographical assessment of the extent and probabilities for yield increase resulting from the maximum-transpiration trait. These results are to be used to geographically target regions where incorporation of the maximum-transpiration trait into commercial varieties would result in consistent yield gains.